Summary:
When destroying a SurfaceInterface all callbacks are getting destroyed.
This used to iterate over the callbacks and performing
wl_resource_destroy on them. This triggered the destroy handler which
removes the resource from the callback list. Which means removing from
the list we are iterating on. This could result in a double delete or
accessing invalid memory.

This change copies all callbacks to a temporary list and clears the
normal lists. So the destroy handler does no longer modify the lists
currently being iterated on.

Test Plan: Added a test case which crashed with previous code

Reviewers: #plasma

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D1677