Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20220126...

virtiofsd: Security fix

Fixes: CVE-2022-0358
# gpg: Signature made Wed 26 Jan 2022 10:46:44 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20220126:
  virtiofsd: Drop membership of all supplementary groups (CVE-2022-0358)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>