Add basic CI duing a build and distcheck

Nothing exciting here, it just runs make, make check and make distcheck to verify the current repo builds fine.

Note that I'm using archlinux here because its image gets frequently rebuild and a system update is quite fast. Fedora can take forever to do a dnf update. There are two schools of thought here:

• take something like archlinux which is up-to-date and serves as early warning sign if something breaks. This puts us at the whim of arch though, if they break something we need to fix it or wait to get the CI to build again
• take something that doesn't change (i.e. a self-created image with fixed packages) and run against those. This is more work and maintenance in the CI but gives us the same result every time.

There is no correct approach here, it just depends on preference. Mesa uses approach 2, libinput a hybrid of 1 and 2 (images are rebuilt every week). For what we're doing here, I think the simplest approach is good enough.