htlcswitch: add PermanentFailure to LinkFailureError

htlcswitch/linkfailure.go

@@ -57,6 +57,10 @@ type LinkFailureError struct {
 	// because of this error.
 	ForceClose bool
 
+	// PermanentFailure indicates whether this failure is permanent, and
+	// the channel should not be attempted loaded again.
+	PermanentFailure bool
+
 	// SendData is a byte slice that will be sent to the peer. If nil a
 	// generic error will be sent.
 	SendData []byte