Merge remote-tracking branch 'remotes/stefanha-gitlab/tags/block-pull-request' into staging

Pull request

This contains coroutine poll size scaling, virtiofsd rseq seccomp for new glibc
versions, and the QEMU C virtiofsd deprecation notice.

# gpg: Signature made Mon 14 Feb 2022 17:14:21 GMT
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha-gitlab/tags/block-pull-request:
  util: adjust coroutine pool size to virtio block queue
  Deprecate C virtiofsd
  tools/virtiofsd: Add rseq syscall to the seccomp allowlist

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