Can't build on OSX as of build 1709

[Lee Bieber]

libtool: compile: g++ -DHAVE_CONFIG_H -I. -I. -isystem ./gnulib -isystem ./gnulib -ggdb3 -I/Users/lbieber/repos/install/include -D_THREAD_SAFE -pipe -std=gnu++98 -O3 -Werror -pedantic -Wall -Wundef -Wshadow -fdiagnostics-show-option -Wformat -fno-strict-aliasing -Wno-strict-aliasing -Wextra -Woverloaded-virtual -Wnon-virtual-dtor -Wctor-dtor-privacy -Wno-long-long -Wno-redundant-decls -MT plugin/myisam/mi_key.lo -MD -MP -MF plugin/myisam/.deps/mi_key.Tpo -c plugin/myisam/mi_key.cc -fno-common -DPIC -o plugin/myisam/.libs/mi_key.o
plugin/myisam/mi_key.cc: In function ‘uint32_t _mi_make_key(MI_INFO*, uint32_t, unsigned char*, const unsigned char*, drizzled::internal::my_off_t)’:
plugin/myisam/mi_key.cc:122: error: ‘isnan’ was not declared in this scope
make[2]: *** [plugin/myisam/mi_key.lo] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

The fix is the following:

=== modified file 'plugin/myisam/mi_key.cc'
--- plugin/myisam/mi_key.cc 2010-02-04 08:14:46 +0000
+++ plugin/myisam/mi_key.cc 2010-08-16 15:26:52 +0000
@@ -23,6 +23,9 @@
 #include <math.h>
 #include <cassert>

+using namespace drizzled;
+using namespace std;
+