Don't crash with Qt 5.11+
Summary:
Based on the patch from https://bugs.kde.org/show_bug.cgi?id=371511
See also https://bugreports.qt.io/browse/QTBUG-72260
BUG: 371511
Reviewers: PHID-PROJ-odxxyyfgujhgbu6ergrt, mlaurent
Reviewed By: PHID-PROJ-odxxyyfgujhgbu6ergrt, mlaurent
Subscribers: marten, asturmlechner, kfunk, kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D17563
(cherry picked from commit 91a4ab57a82970bd75eee4a7aee61a7e1c1321ef)