Copy layer repaints to Deleted
If a Toplevel has scheduled layer repaints, then we have to copy them
to Deleted as well. This can happen, for example, when a client loses
shadow right before it gets closed or unmapped.
Reviewers: KWin, graesslin
Reviewed By: KWin, graesslin
Differential Revision: https://phabricator.kde.org/D18786