CI/CD template for ccache builds
We can make it easy for users to implement builds based on
ccache optimization to speed up the process. It seems that we could benefit from it for our internal flow: omnibus-gitlab#3460 (closed)
The MVC could be a
gitlab-ci.yml template people can customize and reuse.
(This feature is part of https://gitlab.com/gitlab-org/gitlab-ce/issues/21624 but there was no proposal so far)