Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2020-02-20' into staging

Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2020-02-20' into staging

Block patches:
- qemu-img convert: New --target-is-zero parameter
- qcow2: Specify non-default compression type flag
- optionally flat output for query-named-block-nodes
- some fixes
- pseudo-creation of images on block devices is now done by a generic
  block layer function

# gpg: Signature made Thu 20 Feb 2020 16:05:34 GMT
# 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-2020-02-20:
  iotests: Test snapshot -l field separation
  block: Fix VM size field width in snapshot dump
  iotests: Test convert -n -B to backing-less target
  qemu-img: Fix convert -n -B for backing-less targets
  iotests: Add test for image creation fallback
  iscsi: Drop iscsi_co_create_opts()
  file-posix: Drop hdev_co_create_opts()
  block: Generic file creation fallback
  block/nbd: Fix hang in .bdrv_close()
  iotests/279: Fix for non-qcow2 formats
  block/backup-top: fix flags handling
  block: always fill entire LUKS header space with zeros
  qemu-img: Add --target-is-zero to convert
  qapi: Allow getting flat output from 'query-named-block-nodes'
  iotests/147: Fix drive parameters
  iotests: Remove the superfluous 2nd check for the availability of quorum
  docs: qcow2: introduce compression type feature
  docs: improve qcow2 spec about extending image header

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