[gtk+] Avoid a deprecation warning

[Matthias Clasen <matthiasc src gnome org>]

commit 3ab7645ac180355d9c20ae0f4bd0e1046981a3bf
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jun 1 07:00:18 2016 -0400

    Avoid a deprecation warning

 gtk/gtksizegroup.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtksizegroup.c b/gtk/gtksizegroup.c
index cf7c152..a939a05 100644
--- a/gtk/gtksizegroup.c
+++ b/gtk/gtksizegroup.c
@@ -291,7 +291,9 @@ gtk_size_group_set_property (GObject      *object,
       gtk_size_group_set_mode (size_group, g_value_get_enum (value));
       break;
     case PROP_IGNORE_HIDDEN:
+G_GNUC_BEGIN_IGNORE_DEPRECATIONS
       gtk_size_group_set_ignore_hidden (size_group, g_value_get_boolean (value));
+G_GNUC_END_IGNORE_DEPRECATIONS
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);