Install xdg mimetype definition for OpenCL C
Summary:
Installing this mimetype ourselves to complete the
system mimetype db will help people for now.
Reviewers: KDevelop, qi437103, aaronpuchert, kfunk
Reviewed By: KDevelop, kfunk
Subscribers: nalvarez, kdevelop-devel
Differential Revision: https://phabricator.kde.org/D5621