Don't detach list of damaged windows when sending 'done' events

Summary: Most likely, someone forgot to add `qAsConst`.

Reviewers: #kwin, broulik

Reviewed By: broulik

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D13830

composite.cpp

@@ -755,7 +755,7 @@ void Compositor::performCompositing()
     m_timeSinceStart += m_timeSinceLastVBlank;
 
     if (waylandServer()) {
-        for (Toplevel *win : damaged) {
+        for (Toplevel *win : qAsConst(damaged)) {
             if (auto surface = win->surface()) {
                 surface->frameRendered(m_timeSinceStart);
             }