Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2017-08-15' into staging

Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2017-08-15' into staging

nbd patches for 2017-08-15

- Eric Blake: nbd: Fix trace message for disconnect
- Stefan Hajnoczi: qemu-iotests: step clock after each test iteration
- Fam Zheng: 0/4 block: Fix non-shared storage migration
- Eric Blake: nbd-client: Fix regression when server sends garbage

# gpg: Signature made Tue 15 Aug 2017 16:06:02 BST
# gpg:                using RSA key 0xA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>"
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>"
# gpg:                 aka "[jpeg image of size 6874]"
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2017-08-15:
  nbd-client: Fix regression when server sends garbage
  iotests: Add non-shared storage migration case 192
  block-backend: Defer shared_perm tightening migration completion
  nbd: Fix order of bdrv_set_perm and bdrv_invalidate_cache
  stubs: Add vm state change handler stubs
  qemu-iotests: step clock after each test iteration
  nbd: Fix trace message for disconnect

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