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/msw/frame.cpp

@@ -38,6 +38,7 @@
     #include "wx/log.h"
     #include "wx/toolbar.h"
     #include "wx/statusbr.h"
+    #include "wx/menuitem.h"
 #endif // WX_PRECOMP
 
 #include "wx/msw/private.h"
@@ -53,8 +54,6 @@
 
 #include "wx/generic/statusbr.h"
 
-#include "wx/menuitem.h"
-
 #ifdef __WXUNIVERSAL__
     #include "wx/univ/theme.h"
     #include "wx/univ/colschem.h"