The below error is generated when building. I resolved it by completely commenting out lines 312-320 on my_pthread.h where #define sigset(A,B)
was - looks like this section is getting macro expanded wrongly before the (line:390) #ifdef HAVE_DARWIN_THREADS section.

/Users/cdev/mariadb-native-client/include/my_pthread.h:312:21: note: expanded from macro 'sigset'
#define sigset(A,B) do { struct sigaction s; sigset_t set; \
^
In file included from /Users/cdev/mariadb-native-client/libmysql/net.c:31:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/signal.h:97:11: error: expected ')'
/Users/cdev/mariadb-native-client/include/my_pthread.h:312:21: note: expanded from macro 'sigset'
#define sigset(A,B) do { struct sigaction s; sigset_t set; \
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/signal.h:97:9: note: to match this '('
void (*sigset(int, void (int)))(int);
^
1 warning and 2 errors generated.