Add type cast for clarity

src/slurmctld/controller.c

@@ -206,7 +206,7 @@ int main(int argc, char *argv[])
 	slurmctld_lock_t config_write_lock = {
 		WRITE_LOCK, WRITE_LOCK, WRITE_LOCK, WRITE_LOCK };
 	assoc_init_args_t assoc_init_arg;
-	pthread_t assoc_cache_thread = 0;
+	pthread_t assoc_cache_thread = (pthread_t) 0;
 	/*
 	 * Establish initial configuration
 	 */