make pthread_join work on the Mac

Author: kroening

src/ansi-c/library/pthread_lib.c

@@ -344,12 +344,12 @@ inline int pthread_join(pthread_t thread, void **value_ptr)
 #define __CPROVER_ERRNO_H_INCLUDED
 #endif
 
-#ifdef __APPLE_
+#ifdef __APPLE__
 extern __CPROVER_bool __CPROVER_threads_exited[];
 extern __CPROVER_thread_local unsigned long __CPROVER_thread_id;
 extern unsigned long __CPROVER_next_thread_id;
 
-inline int pthread_join(pthread_t thread, void **value_ptr)
+inline int _pthread_join(pthread_t thread, void **value_ptr)
 {
   __CPROVER_HIDE:;