Merge remote-tracking branch 'remotes/xanclic/tags/pull-block-2018-07-09' into staging

Block patches for 3.0-rc0:
- qcow2 metadata overlap protection for the persistent bitmap directory
- Various bug fixes

# gpg: Signature made Mon 09 Jul 2018 19:54:38 BST
# gpg:                using RSA key F407DB0061D5CF40
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/xanclic/tags/pull-block-2018-07-09:
  qcow2: add overlap check for bitmap directory
  iotests: Add VMDK backing file correlation test
  vmdk: Fix possible segfault with non-VMDK backing
  raw: Drop superfluous semicolon
  qcow2: Drop unreachable break
  file-posix: Fix fd_open check in raw_co_copy_range_to
  qcow2: Drop unused cluster_data

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