db/upnp: use "override" instead of "virtual"

src/db/plugins/upnp/Directory.cxx

@@ -124,7 +124,7 @@ public:
 	}
 
 protected:
-	virtual void StartElement(const XML_Char *name, const XML_Char **attrs)
+	void StartElement(const XML_Char *name, const XML_Char **attrs) override
 	{
 		if (object.type != UPnPDirObject::Type::UNKNOWN &&
 		    tag_type == TAG_NUM_OF_ITEM_TYPES) {
@@ -188,7 +188,7 @@ protected:
 		}
 	}
 
-	virtual void EndElement(const XML_Char *name)
+	void EndElement(const XML_Char *name) override
 	{
 		if (tag_type != TAG_NUM_OF_ITEM_TYPES) {
 			assert(object.type != UPnPDirObject::Type::UNKNOWN);
@@ -212,7 +212,7 @@ protected:
 		state = NONE;
 	}
 
-	virtual void CharacterData(const XML_Char *s, int len)
+	void CharacterData(const XML_Char *s, int len) override
 	{
 		if (tag_type != TAG_NUM_OF_ITEM_TYPES) {
 			assert(object.type != UPnPDirObject::Type::UNKNOWN);

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -77,9 +77,9 @@ public:
 	static Database *Create(EventLoop &loop, DatabaseListener &listener,
 				const ConfigBlock &block);
 
-	virtual void Open() override;
-	virtual void Close() override;
-	virtual const LightSong *GetSong(const char *uri_utf8) const override;
+	void Open() override;
+	void Close() override;
+	const LightSong *GetSong(const char *uri_utf8) const override;
 	void ReturnSong(const LightSong *song) const override;
 
 	void Visit(const DatabaseSelection &selection,