Bug#12779790 COMPILATION FAILS OS X 10.7 - IMPLICIT DECLARATION OF

FUNCTION 'PTHREAD_INIT' 

The problem was that compilation would fail with a warning:
Implicit declaration of function 'pthread_init' if MySQL was
compiled on OS X 10.7 (Lion). The reason was that pthread_init()
is now part of an internal OS X pthread library so it was found
by CMake.

This patch fixes the problem by removing HAVE_PTHREAD_INIT and
related code. pthread_init() was specific to MIT-pthreads which
has not been supported since 4.1 and was therefore no longer
relevant.

No test case added.

dbug/tests.c

@@ -44,9 +44,6 @@ int main (int argc, char *argv[])
   if (argc == 1)
     return 0;
 
-#if defined(HAVE_PTHREAD_INIT)
-  pthread_init();                       /* Must be called before DBUG_ENTER */
-#endif
   my_thread_global_init();
 
   dup2(1, 2);