server: re-introduce the quit channel to the server

This commit re-introduces the quit channel to the server as an upcoming
addition needs to synchronize its shutdown with the lifetime of the
server.

server.go

@@ -82,8 +82,8 @@ type server struct {
 	// advertised to other nodes.
 	globalFeatures *lnwire.FeatureVector
 
-	// localFeatures is an feature vector which represent the features which
+	// localFeatures is an feature vector which represent the features
-	// only affect the protocol between these two nodes.
+	// which only affect the protocol between these two nodes.
 	localFeatures *lnwire.FeatureVector
 
 	// currentNodeAnn is the node announcement that has been broadcast to
@@ -91,6 +91,8 @@ type server struct {
 	// changed since last start.
 	currentNodeAnn *lnwire.NodeAnnouncement
 
+	quit chan struct{}
+
 	wg sync.WaitGroup
 }
 
@@ -137,6 +139,8 @@ func newServer(listenAddrs []string, chanDB *channeldb.DB, cc *chainControl,
 
 		globalFeatures: globalFeatures,
 		localFeatures:  localFeatures,
+
+		quit: make(chan struct{}),
 	}
 
 	// If the debug HTLC flag is on, then we invoice a "master debug"
@@ -364,6 +368,8 @@ func (s *server) Stop() error {
 		return nil
 	}
 
+	close(s.quit)
+
 	// Shutdown the wallet, funding manager, and the rpc server.
 	s.cc.chainNotifier.Stop()
 	s.chanRouter.Stop()