more socket cleanup to allow using wxSocket from both wxBase and wxCore (replaces patch 1756260)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50831 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/motif/private.h

@@ -13,7 +13,8 @@
 #define _WX_PRIVATE_H_
 
 #include "wx/defs.h"
-#include "X11/Xlib.h"
+#include <X11/Xlib.h>
+#include <Xm/Xm.h>
 #include "wx/evtloop.h"
 
 class WXDLLIMPEXP_FWD_CORE wxFont;