Merge branch 'msw-headerctrl' of https://github.com/MaartenBent/wxWidgets

Fix applying style of MSW wxHeaderCtrl and add tests for doing it to the
widgets sample.

See https://github.com/wxWidgets/wxWidgets/pull/1710

include/wx/msw/headerctrl.h

@@ -72,10 +72,6 @@ private:
     // Events.
     void OnSize(wxSizeEvent& event);
 
-    // Style flag helper function.
-    long ApplyHeaderReorderFlagToStyle(long style);
-
-
     // The native header control.
     wxMSWHeaderCtrl* m_nativeControl;
     friend class wxMSWHeaderCtrl;