Add Fontconfig find modudle
Summary: Originally coming from KWin, but now also needed by qtbase.
Reviewers: cgiboudeaux
Reviewed By: cgiboudeaux
Subscribers: kossebau, apol, cgiboudeaux, kde-frameworks-devel, kde-buildsystem
Tags: Frameworks, Build System
Differential Revision: https://phabricator.kde.org/D18943