The $CI environment variable may be generally set by Github or Gitlab
actions, and is not a reliable indicator of whether we are running "CI".
It could also, for an absolutely random example that didn't *just
happen*, be Alpine Linux's attempt to enable the Meson testsuite in
their packaging, which... uses Gitlab CI.
In this case, we do want to perform normal skipping on not-found
requirements. Instead of checking for $CI, check for $MESON_CI_JOBNAME
as we already use that in all of our own CI jobs for various reasons.
This makes it easier for linux distros to package Meson without
accumulating hacks like "run the testsuite using `env -u CI`".
Previously the meson test case would only test boost-python on linux.
With the #7909 it is now possible to use boost-python on macOS/homebrew.
This enables the boost-python test on both linux and macOS.
It also uses python.extension_module() instead of shared_library to make the
python extension module.
Set MESON_CI_JOBNAME for all CI jobs which run project tests.
(Note that ${{ github.job }} is the literal job.id used in the yaml, not
any name given to the job with job.id.name, and so is the same for all
matrix entries, and thus not suitable for our purposes there).
Jan Tojnar
Eli Schwartz
Dylan Baker
Daniel Mensinger
Kevin Meagher
Xavier Claessens
Jon Turney