Backport another straightforward deprecation fix

src/frontends/qt4/DockView.h

@@ -38,7 +38,7 @@ public:
 	         Qt::DockWidgetArea area = Qt::LeftDockWidgetArea, ///< Position of
 															   ///the dock (and
 															   ///also drawer)
-	         Qt::WindowFlags flags = 0);
+	         Qt::WindowFlags flags = {});
 
 	virtual ~DockView() {}
 

src/frontends/qt4/FindAndReplace.h

@@ -78,7 +78,7 @@ public:
 	FindAndReplace(
 		GuiView & parent, ///< the main window where to dock.
 		Qt::DockWidgetArea area = Qt::RightDockWidgetArea, ///< Position of the dock (and also drawer)
-		Qt::WindowFlags flags = 0);
+		Qt::WindowFlags flags = {});
 
 	~FindAndReplace();
 

src/frontends/qt4/GuiProgressView.h

@@ -47,7 +47,7 @@ public:
 	GuiProgressView(
 		GuiView & parent, ///< the main window where to dock.
 		Qt::DockWidgetArea area, ///< Position of the dock (and also drawer)
-		Qt::WindowFlags flags = 0);
+		Qt::WindowFlags flags = {});
 
 	~GuiProgressView();
 	/// Controller inherited method.

src/frontends/qt4/GuiSetBorder.h

@@ -26,7 +26,7 @@ class GuiSetBorder : public QWidget
 {
 	Q_OBJECT
 public:
-	GuiSetBorder(QWidget * parent = 0, Qt::WindowFlags fl = 0);
+	GuiSetBorder(QWidget * parent = 0, Qt::WindowFlags fl = {});
 
 	// We need tristate for multi-cell selection
 	enum BorderState {

src/frontends/qt4/GuiSpellchecker.h

@@ -65,7 +65,7 @@ public:
 	GuiSpellchecker(
 		GuiView & parent, ///< the main window where to dock.
 		Qt::DockWidgetArea area = Qt::RightDockWidgetArea, ///< Position of the dock (and also drawer)
-		Qt::WindowFlags flags = 0);
+		Qt::WindowFlags flags = {});
 	~GuiSpellchecker();
 
 private:

src/frontends/qt4/GuiToc.h

@@ -32,7 +32,7 @@ public:
 	GuiToc(
 		GuiView & parent, ///< the main window where to dock.
 		Qt::DockWidgetArea area = Qt::LeftDockWidgetArea, ///< Position of the dock (and also drawer)
-		Qt::WindowFlags flags = 0);
+		Qt::WindowFlags flags = {});
 
 	///
 	bool initialiseParams(std::string const & data);

src/frontends/qt4/GuiViewSource.h

@@ -100,7 +100,7 @@ public:
 	GuiViewSource(
 		GuiView & parent, ///< the main window where to dock.
 		Qt::DockWidgetArea area = Qt::BottomDockWidgetArea, ///< Position of the dock (and also drawer)
-		Qt::WindowFlags flags = 0);
+		Qt::WindowFlags flags = {});
 
 	/// Controller inherited method.
 	///@{