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

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

Pull request

No user-visible changes.

# gpg: Signature made Mon 14 Jan 2019 16:32:19 GMT
# gpg:                using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <[email protected]>"
# gpg:                 aka "Stefan Hajnoczi <[email protected]>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  aio-posix: Fix concurrent aio_poll/set_fd_handler.
  aio-posix: Unregister fd from ctx epoll when removing fd_handler.

Signed-off-by: Peter Maydell <[email protected]>