Add override statements to please clang

Eventually, all overridden virtual methods should be marked properly.
Currently, clang only warns about those in classes that already use
override in at least one place (which was the case dor GuiApplication).

(cherry picked from commit c8f4b68423)

src/frontends/qt4/GuiApplication.h

@@ -63,21 +63,21 @@ public:
 
 	/// \name Methods inherited from Application class
 	//@{
-	DispatchResult const & dispatch(FuncRequest const &);
+	DispatchResult const & dispatch(FuncRequest const &) override;
-	void dispatch(FuncRequest const &, DispatchResult & dr);
+	void dispatch(FuncRequest const &, DispatchResult & dr) override;
-	FuncStatus getStatus(FuncRequest const & cmd) const;
+	FuncStatus getStatus(FuncRequest const & cmd) const override;
-	void restoreGuiSession();
+	void restoreGuiSession() override;
-	Buffer const * updateInset(Inset const * inset) const;
+	Buffer const * updateInset(Inset const * inset) const override;
-	int exec();
+	int exec() override;
-	void exit(int status);
+	void exit(int status) override;
-	bool event(QEvent * e);
+	bool event(QEvent * e) override;
-	bool getRgbColor(ColorCode col, RGBColor & rgbcol);
+	bool getRgbColor(ColorCode col, RGBColor & rgbcol) override;
-	std::string const hexName(ColorCode col);
+	std::string const hexName(ColorCode col) override;
-	void registerSocketCallback(int fd, SocketCallback func);
+	void registerSocketCallback(int fd, SocketCallback func) override;
-	void unregisterSocketCallback(int fd);
+	void unregisterSocketCallback(int fd) override;
-	bool searchMenu(FuncRequest const & func, docstring_list & names) const;
+	bool searchMenu(FuncRequest const & func, docstring_list & names) const override;
-	void handleKeyFunc(FuncCode action);
+	void handleKeyFunc(FuncCode action) override;
-	bool unhide(Buffer * buf); //override
+	bool unhide(Buffer * buf) override;
 	//@}
 
 	///
@@ -105,13 +105,13 @@ public:
 
 	/// \name Methods inherited from QApplication class
 	//@{
-	bool notify(QObject * receiver, QEvent * event);
+	bool notify(QObject * receiver, QEvent * event) override;
 	void commitData(QSessionManager & sm);
 #ifdef Q_WS_X11
-	bool x11EventFilter(XEvent * ev);
+	bool x11EventFilter(XEvent * ev) override;
 #elif defined(QPA_XCB)
 	virtual bool nativeEventFilter(const QByteArray & eventType, void * message,
-	                               long * result) Q_DECL_OVERRIDE;
+	                               long * result) override;
 #endif
 	//@}
 
@@ -196,13 +196,13 @@ public:
 	void gotoBookmark(unsigned int idx, bool openFile, bool switchToBuffer);
 
 	/// Start a long operation with some cancel possibility (button or ESC)
-	void startLongOperation();
+	void startLongOperation() override;
 	/// This needs to be periodically called to avoid freezing the GUI
-	bool longOperationCancelled();
+	bool longOperationCancelled() override;
 	/// Stop the long operation mode (i.e., release the GUI)
-	void stopLongOperation();
+	void stopLongOperation() override;
 	/// A started long operation is still in progress ?
-	bool longOperationStarted();
+	bool longOperationStarted() override;
 private Q_SLOTS:
 	///
 	void execBatchCommands();

status.23x

@@ -141,3 +141,5 @@ What's new
 
 - Update bundled boost distribution to 1.68.
 
+- Fix warnings with clang 7.
+