Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2017-07-10-v2' into staging

nbd patches for 2017-07-10

- Eric Blake: MAINTAINERS: Promote NBD to supported, with new maintainer
- Vladimir Sementsov-Ogievskiy: [00/10] nbd refactoring part 2

# gpg: Signature made Mon 10 Jul 2017 15:59:18 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-2017-07-10-v2:
  nbd: use generic trace subsystem instead of TRACE macro
  nbd: refactor tracing
  nbd/server: rename clientflags var in nbd_negotiate_options
  nbd/server: fix TRACE in nbd_negotiate_send_rep_len
  nbd/client: refactor TRACE of NBD_MAGIC
  nbd/common: nbd_tls_handshake: remove extra TRACE
  nbd/server: add errp to nbd_send_reply()
  nbd/server: use errp instead of LOG
  nbd/server: refactor nbd_negotiate
  nbd/server: nbd_negotiate: return 1 on NBD_OPT_ABORT
  MAINTAINERS: Promote NBD to supported, with new maintainer

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