I find it more readable with some empty lines here and there

Thanks Martin for providing these information :)

Add a cirrus CI config file that runs the regression suite on linux amd64/aarch64 and on freebsd.

While there, use it in the tests too

We ended up copying too much data from the fastcgi process.

It's now possible to run only a subset of the tests with: ./runtime test1 test2 ...

The tests are still there, the suite is equivalent to the old one, but this one is better structured. The biggest annoyance I had with the old one was that it wasn't straightforward to test only a specific set of tests. It's still impossible, but it's way easier to do it now. This extract all the tests to their own functions. It's overall better in all possible regards.