htlcswith/link: resend fundingLocked from channelLink when numUpdates == 0.

In the case where the channelLink get started and the number of
updates on this channel is zero, this means no paymenys has been
done using this channel. This might mean that the fundingLocked
never was sent successfully, so we resend to make sure this
channel gets opened correctly.

htlcswitch/mock.go

@@ -280,6 +280,9 @@ func (s *mockServer) readHandler(message lnwire.Message) error {
 		targetChan = msg.ChanID
 	case *lnwire.CommitSig:
 		targetChan = msg.ChanID
+	case *lnwire.FundingLocked:
+		// Ignore
+		return nil
 	default:
 		return errors.New("unknown message type")
 	}