The JUnit cover report is useful, but only up to a point; for instance,
it's not used unless it's part of a merge request. This means you don't
get a report if you're pushing to a branch that does not have an MR open.
With a simple Python script and some minimal templating, we can generate
an HTML report from the "I Can't Believe it's not JSON™" log that Meson
produces, and keep it as a CI artifact.
The Fedora base image we use for our CI doesn't always keep Meson up to
date with our requirements, so it's better if we just install Meson via
Python's pip.
xvfb doesn't like C.utf8 and returns XLocaleNotSupported.
While (afaik) C.utf8 and C.UTF.8 should be the same thing, and the former
is returned by locale -a on Fedora, switch to C.UTF-8 to make xvfb happy.
This makes gtk+:gdk tests pass.
The GitLab cache is kept across jobs, whether they succeeded or not:
this means that if a compiler check fails during the Meson
configuration, the small compiler program gets cached and restored the
next time the job is run, thus failing again.
