Misc build and test fixes:
- force NOUSER for base docker images
- don't run TCG VM tests by default
- remove useless meson test
- add Centos 8 custom runner
- split up custom-runners to individual files
- skip cirrus checks on master/stable branches
# gpg: Signature made Tue 16 Nov 2021 05:22:09 PM CET
# gpg: using RSA key
6685AE99E75167BCAFC8DF35FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>" [full]
* tag 'pull-for-6.2-161121-1' of https://github.com/stsquad/qemu:
gitlab: skip cirrus jobs on master and stable branches
gitlab-ci: Split custom-runners.yml in one file per runner
Jobs based on custom runners: add CentOS Stream 8
meson: remove useless libdl test
tests/vm: don't build using TCG by default
tests/vm: sort the special variable list
tests/docker: force NOUSER=1 for base images
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>