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

Block layer patches for 2.10.0-rc1

# gpg: Signature made Tue 01 Aug 2017 17:10:52 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:
  block/qapi: Remove redundant NULL check to silence Coverity
  qemu-iotests/059: Fix leaked image files
  qemu-iotests/063: Fix leaked image
  qemu-iotests/162: Fix leaked temporary files
  qemu-iotests/153: Fix leaked scratch images
  qemu-iotests/141: Fix image cleanup
  qemu-iotests: Remove blkdebug.conf after tests
  qemu-iotests/041: Fix leaked scratch images
  block: fix leaks in bdrv_open_driver()
  block: fix dangling bs->explicit_options in block.c
  iotests: Add test of recent fix to 'qemu-img measure'
  iotests: Check dirty bitmap statistics in 124
  iotests: Redirect stderr to stdout in 186
  iotests: Fix test 156

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