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

demos/life/dialogs.h

@@ -37,7 +37,7 @@ class LifeSamplesDialog : public wxDialog
 public:
     // ctor and dtor
     LifeSamplesDialog(wxWindow *parent);
-    ~LifeSamplesDialog();
+    virtual ~LifeSamplesDialog();
 
     // members
     const LifePattern& GetPattern();