Run tools/check-argument-comments.py over the sources that are compiled,
one test per top-level source directory, in a suite that a plain "meson
test" leaves out like the other linters. The NSS, PAM and cryptsetup
token modules don't end up in sources, so collect theirs as well. The
source directory is passed explicitly, so the suite works without git,
from a tarball say. The script exits with meson's skip code where the
libclang python bindings are missing.