Merge remote-tracking branch 'remotes/famz/tags/docker-and-block-pull-request' into staging

Docker and block patches

Two fairly small fixes.

# gpg: Signature made Fri 18 May 2018 10:17:06 BST
# gpg:                using RSA key CA35624C6A9171C6
# gpg: Good signature from "Fam Zheng <famz@redhat.com>"
# Primary key fingerprint: 5003 7CB7 9706 0F76 F021  AD56 CA35 624C 6A91 71C6

* remotes/famz/tags/docker-and-block-pull-request:
  iothread: fix epollfd leak in the process of delIOThread
  docker: Fix trivial typo

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