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

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

# gpg: Signature made Tue 09 Feb 2016 15:11:25 GMT using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/block-pull-request:
  block: add missing call to bdrv_drain_recurse
  blockjob: Fix hang in block_job_finish_sync
  iov: avoid memcpy for "simple" iov_from_buf/iov_to_buf

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