use wxOVERRIDE in wxMSW sources

include/wx/msw/msgdlg.h

@@ -24,9 +24,9 @@ public:
         m_hook = NULL;
     }
 
-    virtual int ShowModal();
+    virtual int ShowModal() wxOVERRIDE;
 
-    virtual long GetEffectiveIcon() const;
+    virtual long GetEffectiveIcon() const wxOVERRIDE;
 
     // implementation-specific
 
@@ -35,7 +35,7 @@ public:
 
 protected:
     // Override this as task dialogs are always centered on parent.
-    virtual void DoCentre(int dir);
+    virtual void DoCentre(int dir) wxOVERRIDE;
 
 private:
     // hook procedure used to adjust the message box beyond what the standard