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

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39123 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/sashwin.cpp

@@ -20,19 +20,20 @@
 
 #if wxUSE_SASH
 
+#include "wx/sashwin.h"
+
 #ifndef WX_PRECOMP
     #include "wx/dialog.h"
     #include "wx/frame.h"
     #include "wx/settings.h"
     #include "wx/dcclient.h"
+    #include "wx/dcscreen.h"
 #endif
 
 #include "wx/math.h"
 
 #include <stdlib.h>
 
-#include "wx/dcscreen.h"
-#include "wx/sashwin.h"
 #include "wx/laywin.h"
 
 DEFINE_EVENT_TYPE(wxEVT_SASH_DRAGGED)