Ignore parent scopes that are in the process of being removed
Summary:
When we destroy a colorscope, all children will try to reparent. This patch
makes it so they never pick an object if it's being removed.
Test Plan:
The logout screen greeter and kscreenlocker doesn't crash anymore
upon close.
Reviewers: Plasma, mart
Reviewed By: Plasma, mart
Subscribers: kde-frameworks-devel
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D25953