mark all dtors which are virtual because base class dtor is virtual explicitly virtual themselves

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41020 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/cocoa/dcscreen.h

@@ -20,7 +20,7 @@ class WXDLLEXPORT wxScreenDC: public wxDC
 public:
     wxScreenDC(void);
     wxScreenDC( wxDC *dc ); // Create compatible DC
-    ~wxScreenDC(void);
+    virtual ~wxScreenDC(void);
 
     // Compatibility with X's requirements for drawing on top of all windows
     static bool StartDrawingOnTop(wxWindow* WXUNUSED(window)) { return true; }