Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2017-09-06' into staging

nbd patches for 2017-09-06

- Daniel P. Berrange: [0/2] Fix / skip recent iotests with LUKS driver
- Eric Blake: [0/3] nbd: Use common read/write-all qio functions

# gpg: Signature made Wed 06 Sep 2017 16:17:55 BST
# gpg:                using RSA key 0xA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <[email protected]>"
# gpg:                 aka "Eric Blake (Free Software Programmer) <[email protected]>"
# 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-2017-09-06:
  nbd: Use new qio_channel_*_all() functions
  io: Add new qio_channel_read{, v}_all_eof functions
  io: Yield rather than wait when already in coroutine
  iotests: blacklist 194 with the luks driver
  iotests: rewrite 192 to use _launch_qemu to fix LUKS support

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