WL: unmap mapped windows upon destroy event
WL: unmap mapped windows upon destroy event

Bad clients might emit destroy events before unmapping. This causes big,
bad segfaults in pywlroots by accessing things on the surface that
should no longer be accessed. Let's unmap them before continuing with
handling their destruction and unmanagement.

ramnes/qtile,qtile/qtile,qtile/qtile,ramnes/qtile