Remove unused parts of wxMSW wxBitmapButton implementation

Nothing here, including the event table for this class using
non-existing wxBitmapButton::OnSysColourChanged (which is just the same
as wxWindow::OnSysColourChanged, in fact), was needed any longer ever
since the changes of a6fd73d33a (implement wxBitmapButton as just a
wrapper for wxButton under MSW, 2009-06-15), so simply remove all the
unused stuff.

include/wx/msw/bmpbuttn.h

@@ -45,7 +45,6 @@ public:
                            wxWindowID winid,
                            const wxString& name = wxString());
 protected:
-    wxDECLARE_EVENT_TABLE();
     wxDECLARE_DYNAMIC_CLASS_NO_COPY(wxBitmapButton);
 };
 

src/msw/bmpbuttn.cpp

@@ -16,29 +16,10 @@
 
 #include "wx/bmpbuttn.h"
 
-#ifndef WX_PRECOMP
-    #include "wx/log.h"
-    #include "wx/dcmemory.h"
-    #include "wx/image.h"
-#endif
-
-#include "wx/msw/private.h"
-#include "wx/msw/dc.h"          // for wxDCTemp
-
-#include "wx/msw/uxtheme.h"
-
-#ifndef ODS_NOFOCUSRECT
-    #define ODS_NOFOCUSRECT     0x0200
-#endif
-
 // ----------------------------------------------------------------------------
-// macros
+// wxBitmapButton implementation
 // ----------------------------------------------------------------------------
 
-wxBEGIN_EVENT_TABLE(wxBitmapButton, wxBitmapButtonBase)
-    EVT_SYS_COLOUR_CHANGED(wxBitmapButton::OnSysColourChanged)
-wxEND_EVENT_TABLE()
-
 /*
 TODO PROPERTIES :