Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-07-15' into staging

Block patches for 4.1-rc1:
- Fixes for the NVMe block driver, the gluster block driver, and for
  running multiple block jobs concurrently on a single chain

# gpg: Signature made Mon 15 Jul 2019 14:51:43 BST
# gpg:                using RSA key 91BEB60A30DB3E8857D11829F407DB0061D5CF40
# gpg:                issuer "mreitz@redhat.com"
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>" [full]
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/maxreitz/tags/pull-block-2019-07-15:
  gluster: fix .bdrv_reopen_prepare when backing file is a JSON object
  iotests: Add read-only test case to 030
  iotests: Add new case to 030
  iotests: Add @use_log to VM.run_job()
  iotests: Compare error messages in 030
  iotests: Fix throttling in 030
  block: Deep-clear inherits_from
  block/stream: Swap backing file change order
  block/stream: Fix error path
  block: Add BDS.never_freeze
  nvme: Set number of queues later in nvme_init()

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