Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20210413...

virtiofs: Fix feature negotiation (for 6.0)

A 6.0 fix for feature negotiation on vhost-user.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
# gpg: Signature made Tue 13 Apr 2021 16:21:41 BST
# 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-20210413:
  vhost-user-fs: fix features handling

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