Clean from non-Q-prefixed signal/slot keywords
Summary:
Adding QT_NO_SIGNALS_SLOTS_KEYWORDS also prevents
any re-sneaking in e.g. to installed headers.
Reviewers: KDevelop, kfunk
Reviewed By: KDevelop, kfunk
Subscribers: kdevelop-devel
Differential Revision: https://phabricator.kde.org/D5279