[gtk+] x11: Use backend-specific API to get GdkScreen

[Emmanuele Bassi <ebassi src gnome org>]

commit d2e9a5fa8850ca0c9673d04316093a2cbcb190b5
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Nov 2 06:42:49 2017 +0000

    x11: Use backend-specific API to get GdkScreen
    
    The gdk_display_get_default_screen() function was removed, but the X11
    GdkEventSource still lobs around GdkX11Screen instances.

 gdk/x11/gdkeventsource.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gdk/x11/gdkeventsource.c b/gdk/x11/gdkeventsource.c
index 0e7657d..80635bf 100644
--- a/gdk/x11/gdkeventsource.c
+++ b/gdk/x11/gdkeventsource.c
@@ -274,7 +274,7 @@ gdk_event_source_translate_event (GdkEventSource *event_source,
   Display *dpy;
   GdkX11Screen *x11_screen;
 
-  x11_screen = (GdkX11Screen*)gdk_display_get_default_screen (event_source->display);
+  x11_screen = (GdkX11Screen *) gdk_x11_display_get_screen (event_source->display); 
 
   dpy = GDK_DISPLAY_XDISPLAY (event_source->display);