Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2019-11-19' into staging

Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2019-11-19' into staging

nbd patches for 2019-11-19

- iotests: more tests of NBD reconnect, various test output improvements
- nbd: fix spec compliance issue with long strings
- slience a Coverity warning on coroutines

# gpg: Signature made Tue 19 Nov 2019 03:06:41 GMT
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2019-11-19:
  tests: More iotest 223 improvements
  iotests: Include QMP input in .out files
  iotests: Switch nbd tests to use Unix rather than TCP
  iotests: Fix 173
  MAINTAINERS: add more bitmap-related to Dirty Bitmaps section
  nbd: Don't send oversize strings
  bitmap: Enforce maximum bitmap name length
  nbd/server: Prefer heap over stack for parsing client names
  qemu-coroutine-sleep: Silence Coverity warning
  iotests: Test NBD client reconnection

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