Merge remote-tracking branch 'remotes/gkurz/tags/9p-next-2020-01-20' into staging

Assorted fixes and cleanups.
v2: - fix 32-bit build

# gpg: Signature made Mon 20 Jan 2020 14:14:11 GMT
# gpg:                using RSA key B4828BAF943140CEF2A3491071D4D5E5822F73D6
# gpg: Good signature from "Greg Kurz <groug@kaod.org>" [full]
# gpg:                 aka "Gregory Kurz <gregory.kurz@free.fr>" [full]
# gpg:                 aka "[jpeg image of size 3330]" [full]
# Primary key fingerprint: B482 8BAF 9431 40CE F2A3  4910 71D4 D5E5 822F 73D6

* remotes/gkurz/tags/9p-next-2020-01-20:
  9pfs/9p.c: remove unneeded labels
  virtfs-proxy-helper.c: remove 'err_out' label in setugid()
  9p: init_in_iov_from_pdu can truncate the size
  9p: local: always return -1 on error in local_unlinkat_common
  9pfs: local: Fix possible memory leak in local_link()

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