Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2019-12-02' into staging

Merge remote-tracking branch 'remotes/armbru/tags/pull-error-2019-12-02' into staging

Error reporting patches for 2019-12-02

# gpg: Signature made Mon 02 Dec 2019 15:17:45 GMT
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-error-2019-12-02:
  block/file-posix: Fix laio_init() error handling crash bug
  net/virtio: Fix failover error handling crash bugs
  net/virtio: Drop useless n->primary_dev not null checks

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