BUG/MINOR: thread: add a check for pthread_create

preload_libgcc_s() use pthread_create to create a thread and then call
pthread_join to use it, but it doesn't check if the option is successful.
So add a check to aviod potential crash.

src/thread.c

@@ -1066,7 +1066,7 @@ static void *dummy_thread_function(void *data)
 static inline void preload_libgcc_s(void)
 {
 	pthread_t dummy_thread;
-	pthread_create(&dummy_thread, NULL, dummy_thread_function, NULL);
+	if (pthread_create(&dummy_thread, NULL, dummy_thread_function, NULL) == 0)
 		pthread_join(dummy_thread, NULL);
 }