htlcswitch: add quit case to initial channel state sync select in channelLink

In this commit we add a quit case to the select statement that’s
entered once a link is created. Before this commit, upon restart it
would be possible that the deamon would never ben able to shutdown as
the link would be waiting for the messages to be sent by the other
side.

htlcswitch/link.go

@@ -297,7 +297,10 @@ func (l *channelLink) Stop() {
 //
 // NOTE: This MUST be run as a goroutine.
 func (l *channelLink) htlcManager() {
-	defer l.wg.Done()
+	defer func() {
+		l.wg.Done()
+		log.Infof("ChannelLink(%v) has exited", l)
+	}()
 
 	log.Infof("HTLC manager for ChannelPoint(%v) started, "+
 		"bandwidth=%v", l.channel.ChannelPoint(), l.Bandwidth())
@@ -367,6 +370,8 @@ func (l *channelLink) htlcManager() {
 			// In any case, we'll then process their ChanSync
 			// message.
 			l.handleUpstreamMsg(msg)
+		case <-l.quit:
+			return
 		case <-chanSyncDeadline:
 			l.fail("didn't receive ChannelReestablish before " +
 				"deadline")
@@ -534,8 +539,6 @@ out:
 			break out
 		}
 	}
-
-	log.Infof("ChannelLink(%v) has exited", l)
 }
 
 // handleDownStreamPkt processes an HTLC packet sent from the downstream HTLC