Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging

Block layer patches

- mirror: Fix active mirror deadlock
- replication: Fix crashes due to operations on wrong BdrvChild
- configure: Add option to use driver whitelist even in tools
- vvfat: Fix crash when opening image read-write
- export: Fix crash in error path with fixed-iothread=false

# gpg: Signature made Tue 20 Jul 2021 16:09:23 BST
# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  iotests/307: Test iothread conflict for exports
  block/export: Conditionally ignore set-context error
  block/vvfat: fix: drop backing
  replication: Remove workaround
  replication: Properly attach children
  replication: Reduce usage of s->hidden_disk and s->secondary_disk
  replication: Remove s->active_disk
  block: Add option to use driver whitelist even in tools
  block/mirror: fix active mirror dead-lock in mirror_wait_on_conflicts
  iotest 151: add test-case that shows active mirror dead-lock
  block/mirror: set .co for active-write MirrorOp objects

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