[gnome-panel] notification-area: fix 'switch missing default case' warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit ecd7eb8c2ad4d1e3d4315ab302afb49714f62fd8
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Oct 30 22:45:15 2016 +0200

    notification-area: fix 'switch missing default case' warning

 applets/notification_area/na-tray.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/applets/notification_area/na-tray.c b/applets/notification_area/na-tray.c
index 6fbee6b..76d6bae 100644
--- a/applets/notification_area/na-tray.c
+++ b/applets/notification_area/na-tray.c
@@ -501,6 +501,9 @@ update_size_and_orientation (NaTray *tray)
     case GTK_ORIENTATION_HORIZONTAL:
       gtk_widget_set_size_request (priv->box, -1, MIN_BOX_SIZE);
       break;
+    default:
+      g_assert_not_reached ();
+      break;
     }
 }