Bug #27964: pthread_key_create doesn't set errno, so don't report \

	errno

Vasil Dimov (at Oracle) noted that pthread_key_create() does not
set errno, so if it fails then we return the wrong error code.

Instead, capture the return value, which is the real error value, 
and instead report that.

mysys/my_thr_init.c

@@ -79,11 +79,12 @@ static uint get_thread_lib(void);
 
 my_bool my_thread_global_init(void)
 {
+  int pth_ret;
   thd_lib_detected= get_thread_lib();
 
-  if (pthread_key_create(&THR_KEY_mysys,0))
+  if (pth_ret= pthread_key_create(&THR_KEY_mysys, NULL))
   {
-    fprintf(stderr,"Can't initialize threads: error %d\n",errno);
+    fprintf(stderr,"Can't initialize threads: pthread error %d\n", pth_ret);
     return 1;
   }