Qt::WFlags is obsolete in Qt5. Replace it with Qt::WindowFlags.

This change is Qt4/Qt5 neutral.

src/Gui/MainWindow.cpp

@@ -236,7 +236,7 @@ protected:
 
 /* TRANSLATOR Gui::MainWindow */
 
-MainWindow::MainWindow(QWidget * parent, Qt::WFlags f)
+MainWindow::MainWindow(QWidget * parent, Qt::WindowFlags f)
   : QMainWindow( parent, f/*WDestructiveClose*/ )
 {
     d = new MainWindowP;