Travis CI timeouts for MacPorts builds

[Ralph Seichter]

* Mojca Miklavec:

> If you volunteer to do some research / work in this area ... that
> would likely be the most significant step in "increasing your chances"

I actually have some experience in this field. I use GitLab (Omnibus
edition), Docker, and GitLab Runners inside Docker for CI/CD. That's
basically the setup which gitlab.com uses (albeit sans their S3-based
caching), and it can handle serious builds.

Doing research re MacPorts would require knowledge about the MP build
infrastructure, which I don't yet have. I'd be willing to look into it,
though, if that infrastructure is properly documented somewhere.

-Ralph