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/html/helpfrm.h

@@ -77,7 +77,7 @@ public:
                     int style = wxHF_DEFAULT_STYLE, wxHtmlHelpData* data = NULL);
     bool Create(wxWindow* parent, wxWindowID id, const wxString& title = wxEmptyString,
                 int style = wxHF_DEFAULT_STYLE);
-    ~wxHtmlHelpFrame();
+    virtual ~wxHtmlHelpFrame();
 
     /// Returns the data associated with the window.
     wxHtmlHelpData* GetData() { return m_Data; }