Bug fix: find c++ stl using regex
Summary:
Find C++ shared lib path using regex. This change makes finding path
independent of the order in which it was added by cmake.
Reviewers: apol
Reviewed By: apol
Subscribers: kde-buildsystem, kde-frameworks-devel
Tags: Frameworks, Build System
Differential Revision: https://phabricator.kde.org/D20558