libdrizzle: Re-using a result struct without freeing causes infinite loop

[Andrew Hutchings]

From Brian:
Just another note, while looking at this I found that the client seemed to go into a loop of some sort at:

#0 drizzle_result_free (result=0x62f868) at libdrizzle/result.c:130
#1 0x00007ffff7ddaeb5 in drizzle_result_free_all (con=0x627248) at libdrizzle/result.c:139
#2 0x00007ffff7dd5ec0 in drizzle_con_free (con=0x627248) at libdrizzle/drizzle.c:392
#3 0x0000000000406bfa in gearman_server_queue_libdrizzle_deinit (server=0x625030) at libgearman-server/queue_libdrizzle.c:307
#4 0x0000000000406998 in gearman_server_queue_libdrizzle_init (server=0x625030, conf=0x7fffffffd980) at libgearman-server/queue_libdrizzle.c:244
#5 0x0000000000406c67 in gearmand_queue_libdrizzle_init (gearmand=0x624fc0, conf=0x7fffffffd980) at libgearman-server/queue_libdrizzle.c:319

[Andrew Hutchings (linuxjedi)]

I first attempted to fix this by having drizzle_query check if the result struct had a DRIZZLE_RESULT_NONE. But when using C++ the status can be random. So fixing by testing if the result pointer is in the list of result sets to be freed.