Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20200210...

Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20200210' into staging

virtiofsd pull 2020-02-10

Coverity fixes and a reworked man page.

# gpg: Signature made Mon 10 Feb 2020 17:26:29 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-20200210:
  docs: add virtiofsd(1) man page
  virtiofsd: do_read missing NULL check
  virtiofsd: load_capng missing unlock
  virtiofsd: fv_create_listen_socket error path socket leak
  virtiofsd: Remove fuse_req_getgroups

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