This adds a generic helper to destory transient globals. See [1]. This patch depends on [2] and [3]. [1]: https://gitlab.freedesktop.org/wayland/wayland/issues/10 [2]: https://gitlab.freedesktop.org/wayland/wayland/merge_requests/28 [3]: https://gitlab.freedesktop.org/wayland/wayland/merge_requests/30