Made wxGTK compile and link again. Broke wxMSW a little.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4098 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk1/dataobj.h

@@ -20,6 +20,10 @@
 
 class wxDataObject : public wxDataObjectBase
 {
+public:
+    wxDataObject();
+
+    virtual bool IsSupportedFormat( const wxDataFormat& format, Direction dir = Get ) const;
 };
 
 #endif // _WX_GTK_DATAOBJ_H_