Fix bug that did not allow for multiple batched RLS notifications to be sent.

A misunderstanding of how the scheduler worked caused further batched notifications
beyond the first not to get scheduled. Now we reset our scheduler ID to -1 after
the batched notification is sent. This way, further notifications can be scheduled
when they arise.
........

Merged revisions 422239 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@422240 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_pjsip_pubsub.c

@@ -1988,6 +1988,7 @@ static int serialized_send_notify(void *userdata)
 	}
 
 	send_notify(sub_tree, 0);
+	sub_tree->notify_sched_id = -1;
 	ao2_cleanup(sub_tree);
 	return 0;
 }