clients/window: Defer closing of window

Instead of closing the window directly by calling close_handler() use a deferred task to do that instead.

That way we avoid a potential invalid access on a link which was previously removed, due to the fact both window_destroy() and touch_handle_up() traverse the same list.

This is an alternative to !841 (closed)

Fixes: #607 (closed).

Suggested-by: Pekka Paalanen pekka.paalanen@collabora.com Reported-by: He Yong hyyoxhk@163.com Signed-off-by: Marius Vlad marius.vlad@collabora.com