[metacity/gnome-3-22] ui: avoid a deprecation warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit df25c0d34d0e65845a7c8541bbc46b3ce2de9dbc
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Mon Oct 24 19:04:38 2016 +0300

    ui: avoid a deprecation warning

 src/ui/ui.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/src/ui/ui.c b/src/ui/ui.c
index 7381c27..ff7b46a 100644
--- a/src/ui/ui.c
+++ b/src/ui/ui.c
@@ -91,7 +91,13 @@ meta_ui_get_display (void)
 gint
 meta_ui_get_screen_number (void)
 {
-  return gdk_screen_get_number (gdk_screen_get_default ());
+  gint screen;
+
+  G_GNUC_BEGIN_IGNORE_DEPRECATIONS
+  screen = gdk_screen_get_number (gdk_screen_get_default ());
+  G_GNUC_END_IGNORE_DEPRECATIONS
+
+  return screen;
 }
 
 /* We do some of our event handling in frames.c, which expects