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 for 2.10.0-rc3

# gpg: Signature made Fri 11 Aug 2017 15:02:58 BST
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  qemu-iotests: fix 185
  file-posix: Do runtime check for ofd lock API
  osdep: Add runtime OFD lock detection
  qcow2: Check failure of bdrv_getlength()
  qcow2: Drop debugging dump_refcounts()
  vpc: Check failure of bdrv_getlength()
  tests/multiboot: Fix whitespace failure

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