wxwidget install failed with GSocket

Problem:
avoid name clashes with GSocket from glib 2.21+

Solution:
#include <stdio.h>
     
// newer versions of glib define its own GSocket but we unfortunately use this
 // name in our own (semi-)public header and so can't change it -- rename glib
// one instead
#define GSocket GlibGSocket
#include <gdk/gdk.h>
#include <glib.h>
#undef GSocket
     
#include "wx/gsocket.h"