I wasn't able to get this to work on CentOS.  When I run this, I get the following:

libgearman-server/plugins/queue/drizzle/queue.cc:24:39: error: libdrizzle/drizzle_client.h: No such file or directory
libgearman-server/plugins/queue/drizzle/queue.cc:46: error: 'drizzle_return_t' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:47: error: expected ',' or ';' before '{' token
libgearman-server/plugins/queue/drizzle/queue.cc:123: error: ISO C++ forbids declaration of 'drizzle_result_st' with no type
libgearman-server/plugins/queue/drizzle/queue.cc:123: error: expected ';' before '*' token
libgearman-server/plugins/queue/drizzle/queue.cc:128: error: expected ';' before 'void'
libgearman-server/plugins/queue/drizzle/queue.cc:148: error: ISO C++ forbids declaration of 'drizzle_st' with no type
libgearman-server/plugins/queue/drizzle/queue.cc:148: error: expected ';' before '*' token
libgearman-server/plugins/queue/drizzle/queue.cc:149: error: ISO C++ forbids declaration of 'drizzle_con_st' with no type
libgearman-server/plugins/queue/drizzle/queue.cc:149: error: expected ';' before '*' token
libgearman-server/plugins/queue/drizzle/queue.cc:150: error: ISO C++ forbids declaration of 'drizzle_con_st' with no type
libgearman-server/plugins/queue/drizzle/queue.cc:150: error: expected ';' before '*' token
libgearman-server/plugins/queue/drizzle/queue.cc:151: error: 'drizzle_result_st' does not name a type
libgearman-server/plugins/queue/drizzle/queue.cc: In constructor 'gearmand::plugins::queue::Drizzle::Drizzle()':
libgearman-server/plugins/queue/drizzle/queue.cc:170: error: class 'gearmand::plugins::queue::Drizzle' does not have any field named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:171: error: class 'gearmand::plugins::queue::Drizzle' does not have any field named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:172: error: class 'gearmand::plugins::queue::Drizzle' does not have any field named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:173: error: class 'gearmand::plugins::queue::Drizzle' does not have any field named '_result'
libgearman-server/plugins/queue/drizzle/queue.cc:189: error: 'drizzle' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:189: error: 'drizzle_create' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:190: error: 'con' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:190: error: 'drizzle_con_create' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:191: error: 'insert_con' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc: In destructor 'virtual gearmand::plugins::queue::Drizzle::~Drizzle()':
libgearman-server/plugins/queue/drizzle/queue.cc:196: error: 'con' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:196: error: 'drizzle_con_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:197: error: 'insert_con' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:198: error: 'drizzle' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:198: error: 'drizzle_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc: At global scope:
libgearman-server/plugins/queue/drizzle/queue.cc:218: error: 'drizzle_return_t' does not name a type
libgearman-server/plugins/queue/drizzle/queue.cc:254: error: 'drizzle_return_t' does not name a type
libgearman-server/plugins/queue/drizzle/queue.cc: In function 'gearmand_error_t gearman_server_queue_libdrizzle_init(gearmand::plugins::queue::Drizzle*, gearman_server_st*)':
libgearman-server/plugins/queue/drizzle/queue.cc:324: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:324: error: 'drizzle_create' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:330: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:330: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:330: error: 'drizzle_con_create' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:336: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:336: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:336: error: 'drizzle_con_create' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:342: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:342: error: 'drizzle_con_set_db' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:343: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:347: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:347: error: 'DRIZZLE_CON_MYSQL' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:347: error: 'drizzle_con_set_options' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:348: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:353: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:353: error: 'drizzle_con_set_tcp' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:354: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:358: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:358: error: 'drizzle_con_set_uds' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:359: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:362: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:362: error: 'drizzle_con_set_auth' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:363: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'insert_con'
libgearman-server/plugins/queue/drizzle/queue.cc:371: error: '_libdrizzle_query' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:371: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:376: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:376: error: 'drizzle_result_buffer' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:376: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:378: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:378: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:381: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:381: error: 'drizzle_result_row_count' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:385: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:385: error: 'drizzle_result_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:390: error: '_libdrizzle_query' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:390: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:392: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:392: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:395: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:395: error: 'drizzle_result_buffer' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:395: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:397: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:397: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:399: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:399: error: 'drizzle_result_row_count' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:400: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:405: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:405: error: 'drizzle_con_db' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:412: error: '_libdrizzle_query' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:412: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:414: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:414: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:417: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:417: error: 'drizzle_column_skip_all' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:417: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:419: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:420: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:420: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:422: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:427: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'con'
libgearman-server/plugins/queue/drizzle/queue.cc:427: error: 'drizzle_con_db' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:432: error: '_libdrizzle_query' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:432: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:434: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:434: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:437: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:437: error: 'drizzle_result_buffer' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:437: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:439: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:439: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:442: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:447: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc: In function 'gearmand_error_t _libdrizzle_add(gearman_server_st*, void*, const char*, size_t, const char*, size_t, const void*, size_t, gearmand_job_priority_t, int64_t)':
libgearman-server/plugins/queue/drizzle/queue.cc:522: error: '_libdrizzle_insert' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:522: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:524: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:524: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc: In function 'gearmand_error_t _libdrizzle_done(gearman_server_st*, void*, const char*, size_t, const char*, size_t)':
libgearman-server/plugins/queue/drizzle/queue.cc:577: error: '_libdrizzle_query' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:577: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:582: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:582: error: 'drizzle_result_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc: In function 'gearmand_error_t _libdrizzle_replay(gearman_server_st*, void*, gearmand_error_t (*)(gearman_server_st*, void*, const char*, size_t, const char*, size_t, const void*, size_t, gearmand_job_priority_t, int64_t), void*)':
libgearman-server/plugins/queue/drizzle/queue.cc:672: error: '_libdrizzle_query' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:672: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:674: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:674: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:677: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:677: error: 'drizzle_column_buffer' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:677: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:679: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:679: error: 'drizzle_result_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:680: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:680: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:685: error: 'drizzle_return_t' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:685: error: expected ';' before 'ret'
libgearman-server/plugins/queue/drizzle/queue.cc:686: error: 'drizzle_row_t' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:686: error: expected ';' before 'row'
libgearman-server/plugins/queue/drizzle/queue.cc:688: error: 'ret' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:688: error: 'libdrizzle_failed' cannot be used as a function
libgearman-server/plugins/queue/drizzle/queue.cc:690: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:690: error: 'drizzle_result_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:691: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'drizzle'
libgearman-server/plugins/queue/drizzle/queue.cc:691: error: 'drizzle_error' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:694: error: 'row' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:699: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:699: error: 'drizzle_row_field_sizes' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:701: error: 'row' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:709: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:709: error: 'drizzle_row_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:710: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:710: error: 'drizzle_result_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:731: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:731: error: 'drizzle_row_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:732: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:732: error: 'drizzle_result_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:736: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:736: error: 'drizzle_row_free' was not declared in this scope
libgearman-server/plugins/queue/drizzle/queue.cc:739: error: 'class gearmand::plugins::queue::Drizzle' has no member named 'result'
libgearman-server/plugins/queue/drizzle/queue.cc:739: error: 'drizzle_result_free' was not declared in this scope
make[1]: *** [libgearman-server/plugins/queue/drizzle/libgearman_server_libgearman_server_la-queue.lo] Error 1
make[1]: Leaving directory `/tmp/gearmand-0.26'
make: *** [all] Error 2


If I change the CFLAGS to include /opt/src/drizzle7-2011.11.29, I'm back to the original problem.