fix code indent.

src/ipc.c

@@ -1140,7 +1140,7 @@ rt_err_t rt_event_recv(rt_event_t   event,
     {
         /* set received event */
         if (recved)
-        	*recved = (event->set & set);
+            *recved = (event->set & set);
 
         /* received event */
         if (option & RT_EVENT_FLAG_CLEAR)