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

src/html/helpwnd.cpp

@@ -93,7 +93,7 @@ class wxHtmlHelpHashData : public wxObject
     public:
         wxHtmlHelpHashData(int index, wxTreeItemId id) : wxObject()
             { m_Index = index; m_Id = id;}
-        ~wxHtmlHelpHashData() {}
+        virtual ~wxHtmlHelpHashData() {}
 
         int m_Index;
         wxTreeItemId m_Id;