TT#111150 fix possible null pointer dereference

Change-Id: I52d8df03fda2e39d353a9c05e264a1ecd13df2ca

daemon/media_player.c

@@ -43,6 +43,8 @@ static void send_timer_send_lock(struct send_timer *st, struct codec_packet *cp)
 #ifdef WITH_TRANSCODING
 // called with call->master lock in W
 static unsigned int send_timer_flush(struct send_timer *st, void *ptr) {
+	if (!st)
+		return 0;
 	return timerthread_queue_flush(&st->ttq, ptr);
 }