create macro to define scheduler function prototypes.

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@5168 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_core.c

@@ -71,7 +71,7 @@ static void send_heartbeat(void)
 	}
 }
 
-static void heartbeat_callback(switch_scheduler_task_t *task)
+SWITCH_STANDARD_SCHED_FUNC(heartbeat_callback)
 {
 	send_heartbeat();