libweston-desktop: Implement xdg_shell_v6

Signed-off-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Acked-by: Giulio Camuffo <giulio.camuffo@kdab.com>

Differential Revision: https://phabricator.freedesktop.org/D1210
diff --git a/libweston/compositor.h b/libweston/compositor.h
index 26667ca..301bdca 100644
--- a/libweston/compositor.h
+++ b/libweston/compositor.h
@@ -1526,6 +1526,8 @@
 			const char *role_name,
 			struct wl_resource *error_resource,
 			uint32_t error_code);
+const char *
+weston_surface_get_role(struct weston_surface *surface);
 
 void
 weston_surface_set_label_func(struct weston_surface *surface,