QAtomicInteger::loadRelaxed() and storeRelaxed() are available since Qt 5.14
Test Plan: make && ctest
Reviewers: Baloo, meven, bruns, astippich, mlaurent
Reviewed By: mlaurent
Subscribers: kde-frameworks-devel
Tags: Frameworks, Baloo
Differential Revision: https://phabricator.kde.org/D26102