fix m_sizerPage memory leak for the wizards not using sizers (replaces patch 1708331, fixes bug 1647290) [backport from HEAD]

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@45723 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/wizard.h

@@ -45,6 +45,10 @@ public:
              long style = wxDEFAULT_DIALOG_STYLE);
     void Init();
 
+#if wxABI_VERSION >= 20804
+    virtual ~wxWizard();
+#endif
+
     // implement base class pure virtuals
     virtual bool RunWizard(wxWizardPage *firstPage);
     virtual wxWizardPage *GetCurrentPage() const;