db/lazy, input/mms: add "override" keywords

src/db/plugins/LazyDatabase.hxx

@@ -43,7 +43,7 @@ public:
 
 	virtual const LightSong *GetSong(const char *uri_utf8,
 					 Error &error) const override;
-	virtual void ReturnSong(const LightSong *song) const;
+	void ReturnSong(const LightSong *song) const override;
 
 	virtual bool Visit(const DatabaseSelection &selection,
 			   VisitDirectory visit_directory,

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -85,7 +85,7 @@ public:
 	virtual void Close() override;
 	virtual const LightSong *GetSong(const char *uri_utf8,
 					 Error &error) const override;
-	virtual void ReturnSong(const LightSong *song) const;
+	void ReturnSong(const LightSong *song) const override;
 
 	virtual bool Visit(const DatabaseSelection &selection,
 			   VisitDirectory visit_directory,
@@ -101,7 +101,9 @@ public:
 	virtual bool GetStats(const DatabaseSelection &selection,
 			      DatabaseStats &stats,
 			      Error &error) const override;
-	virtual time_t GetUpdateStamp() const {return 0;}
+	time_t GetUpdateStamp() const override {
+		return 0;
+	}
 
 protected:
 	bool Configure(const config_param &param, Error &error);

src/input/plugins/MmsInputPlugin.cxx

@@ -43,7 +43,7 @@ protected:
 	virtual size_t ThreadRead(void *ptr, size_t size,
 				  Error &error) override;
 
-	virtual void Close() {
+	void Close() override {
 		mmsx_close(mms);
 	}
 };