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

Block patches

One fix from Paolo on nvme:// driver.
One fix from Marc-Andre for iothread.

# gpg: Signature made Fri 12 Oct 2018 02:49:42 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/block-pull-request:
  nvme: correct locking around completion
  iothread: fix crash with invalid properties

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