Only cleanup XRenderUtils is we actually created it
Summary: BUG: 386430
Test Plan:
kwin_x11 --crashes 20
Got a dialog. Hit cancel. It didn't crash
Reviewers: Plasma, graesslin
Reviewed By: Plasma, graesslin
Subscribers: plasma-devel, kwin, KWin
Tags: KWin
Differential Revision: https://phabricator.kde.org/D8593