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/motif/dcmemory.h

@@ -21,7 +21,7 @@ class WXDLLIMPEXP_CORE wxMemoryDC : public wxWindowDC
 public:
     wxMemoryDC();
     wxMemoryDC( wxDC *dc ); // Create compatible DC
-    ~wxMemoryDC();
+    virtual ~wxMemoryDC();
 
     virtual void SelectObject( const wxBitmap& bitmap );