When StopMonitor is called, ensure that it will not be restarted by a channel event.

(closes issue #16590)
 Reported by: kkm
 Patches: 
       resmonitor-16590-trunk.239289.diff uploaded by kkm (license 888)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@258775 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_monitor.c

@@ -335,7 +335,9 @@ int ast_monitor_stop(struct ast_channel *chan, int need_lock)
 		free(chan->monitor->format);
 		free(chan->monitor);
 		chan->monitor = NULL;
+		pbx_builtin_setvar_helper(chan, "MONITORED", NULL);
 	}
+	pbx_builtin_setvar_helper(chan, "AUTO_MONITOR", NULL);
 
 	UNLOCK_IF_NEEDED(chan, need_lock);