Merge remote-tracking branch 'remotes/ericb/tags/pull-qapi-2018-03-12-v4' into staging

Merge remote-tracking branch 'remotes/ericb/tags/pull-qapi-2018-03-12-v4' into staging

qapi patches for 2018-03-12, 2.12 softfreeze

- Marc-André Lureau: 0/4 qapi: generate a literal qobject for introspection
- Max Reitz: 0/7 block: Handle null backing link
- Daniel P. Berrange: chardev: tcp: postpone TLS work until machine done
- Peter Xu: 00/23 QMP: out-of-band (OOB) execution support
- Vladimir Sementsov-Ogievskiy: 0/2 block latency histogram
- Eric Blake: qapi: Pass '-u' when doing non-silent diff

# gpg: Signature made Mon 19 Mar 2018 19:59:04 GMT
# gpg:                using RSA key A7A16B4A2527436A
# 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-qapi-2018-03-12-v4: (38 commits)
  qapi: Pass '-u' when doing non-silent diff
  qapi: add block latency histogram interface
  block/accounting: introduce latency histogram
  tests: qmp-test: add oob test
  tests: qmp-test: verify command batching
  qmp: add command "x-oob-test"
  monitor: enable IO thread for (qmp & !mux) typed
  qmp: isolate responses into io thread
  qmp: support out-of-band (oob) execution
  qapi: introduce new cmd option "allow-oob"
  monitor: send event when command queue full
  qmp: add new event "command-dropped"
  monitor: separate QMP parser and dispatcher
  monitor: let suspend/resume work even with QMPs
  monitor: let suspend_cnt be thread safe
  monitor: introduce monitor_qmp_respond()
  qmp: introduce QMPCapability
  monitor: allow using IO thread for parsing
  monitor: let mon_list be tail queue
  monitor: unify global init
  ...

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