Use QTWEBENGINE_VERSION not QT_VERSION for WebEngine feature detection
Summary:
FreeBSD's Qt5WebEngine version is not in sync with the Qt5-version.
Therefore check the version we actually care about here.
Reviewers: Automotive, mlaurent, vkrause
Reviewed By: Automotive, vkrause
Subscribers: kde-pim
Tags: KDE PIM
Differential Revision: https://phabricator.kde.org/D22300