Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2020-09-15' into staging

Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2020-09-15' into staging

Block patches:
- Several qcow2 fixes and refactorings
- Let qemu-img convert try to stay at cluster boundaries
- Stable child names for quorum (with x-blockdev-change)
- Explicitly drop vhdx 4k sector support, as it was never actually
  working
- rbd: Mark @namespace a strong runtime option
- iotests.py improvements
- Drop unused runtime_opts objects
- Skip a test case in 030 when run through make check-block

# gpg: Signature made Tue 15 Sep 2020 11:27:05 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-2020-09-15: (22 commits)
  block/rbd: add 'namespace' to qemu_rbd_strong_runtime_opts[]
  qcow2: Convert qcow2_alloc_cluster_offset() into qcow2_alloc_host_offset()
  qcow2: Make preallocate_co() resize the image to the correct size
  block/qcow: remove runtime opts
  block/rbd: remove runtime_opts
  qcow2: Return the original error code in qcow2_co_pwrite_zeroes()
  qcow2: Make qcow2_free_any_clusters() free only one cluster
  qcow2: Handle QCowL2Meta on error in preallocate_co()
  block/vhdx: Support vhdx image only with 512 bytes logical sector size
  iotests: Skip test_stream_parallel in test 030 when doing "make check"
  qemu-img: Explicit number replaced by a constant
  qcow2: Rewrite the documentation of qcow2_alloc_cluster_offset()
  qcow2: Don't check nb_clusters when removing l2meta from the list
  qcow2: Fix removal of list members from BDRVQcow2State.cluster_allocs
  qcow2: Use macros for the L1, refcount and bitmap table entry sizes
  qemu-img: avoid unaligned read requests during convert
  block/quorum.c: stable children names
  qemu-iotests: Simplify FilePath __init__
  qemu-iotests: Merge FilePaths and FilePath
  qemu-iotests: Support varargs syntax in FilePaths
  ...

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