use more wxOVERRIDE (#329)

include/wx/msw/ole/dropsrc.h

@@ -57,12 +57,12 @@ public:
 
     // do it (call this in response to a mouse button press, for example)
     // params: if bAllowMove is false, data can be only copied
-    virtual wxDragResult DoDragDrop(int flags = wxDrag_CopyOnly);
+    virtual wxDragResult DoDragDrop(int flags = wxDrag_CopyOnly) wxOVERRIDE;
 
     // overridable: you may give some custom UI feedback during d&d operation
     // in this function (it's called on each mouse move, so it shouldn't be
     // too slow). Just return false if you want default feedback.
-    virtual bool GiveFeedback(wxDragResult effect);
+    virtual bool GiveFeedback(wxDragResult effect) wxOVERRIDE;
 
 protected:
     void Init();