use common AllocExclusive, rather than custom code

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42072 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/font.h

@@ -84,6 +84,9 @@ protected:
     // common part of all ctors
     void Init();
 
+    virtual wxObjectRefData* CreateRefData() const;
+    virtual wxObjectRefData* CloneRefData(const wxObjectRefData* data) const;
+
 private:
     DECLARE_DYNAMIC_CLASS(wxFont)
 };