Merge remote-tracking branch 'remotes/armbru/tags/pull-monitor-2018-10-30-v2' into...

Merge remote-tracking branch 'remotes/armbru/tags/pull-monitor-2018-10-30-v2' into staging

Monitor patches for 2018-10-30

# gpg: Signature made Tue 06 Nov 2018 17:37:16 GMT
# gpg:                using RSA key 3870B400EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-monitor-2018-10-30-v2:
  vl: Avoid crash when -mon is underspecified
  monitor: delay monitor iothread creation
  monitor: guard iothread access by mon->use_io_thread

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