[mutter] wayland/tablet-pad: Fix fallthrough warning

[Marge Bot <marge-bot src gnome org>]

commit 590e32dc62e9e7b850ccef170c530b044b0e3f34
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Mar 4 20:59:50 2022 +0100

    wayland/tablet-pad: Fix fallthrough warning
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2319>

 src/wayland/meta-wayland-tablet-pad.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/wayland/meta-wayland-tablet-pad.c b/src/wayland/meta-wayland-tablet-pad.c
index c0b408c101..fc108b7959 100644
--- a/src/wayland/meta-wayland-tablet-pad.c
+++ b/src/wayland/meta-wayland-tablet-pad.c
@@ -360,6 +360,7 @@ meta_wayland_tablet_pad_handle_event (MetaWaylandTabletPad *pad,
     case CLUTTER_PAD_STRIP:
       if (group)
         return meta_wayland_tablet_pad_group_handle_event (group, event);
+      G_GNUC_FALLTHROUGH;
     default:
       return FALSE;
     }