Include wx/menuitem.h according to precompiled headers of wx/wx.h (with other minor cleaning).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39787 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/ownerdrw.cpp

@@ -23,11 +23,10 @@
     #include "wx/menu.h"
     #include "wx/utils.h"
     #include "wx/settings.h"
+    #include "wx/menuitem.h"
 #endif
 
 #include "wx/ownerdrw.h"
-#include "wx/menuitem.h"
-
 
 // ============================================================================
 // implementation of wxOwnerDrawn class