Merge remote-tracking branch 'remotes/jnsnow/tags/bitmaps-pull-request' into staging

Pull request

# gpg: Signature made Mon 29 Oct 2018 21:24:08 GMT
# gpg:                using RSA key 7DEF8106AAFC390E
# gpg: Good signature from "John Snow (John Huston) <jsnow@redhat.com>"
# Primary key fingerprint: FAEB 9711 A12C F475 812F  18F2 88A9 064D 1835 61EB
#      Subkey fingerprint: F9B7 ABDB BCAC DF95 BE76  CBD0 7DEF 8106 AAFC 390E

* remotes/jnsnow/tags/bitmaps-pull-request:
  iotests: 169: add cases for source vm resuming
  iotests: improve 169
  dirty-bitmaps: clean-up bitmaps loading and migration logic
  bitmap: Update count after a merge
  nbd: forbid use of frozen bitmaps
  block/backup: prohibit backup from using in use bitmaps
  block/dirty-bitmaps: prohibit enable/disable on locked/frozen bitmaps
  block/dirty-bitmaps: allow clear on disabled bitmaps
  block/dirty-bitmaps: fix merge permissions
  block/dirty-bitmaps: add user_locked status checker
  bloc/qcow2: drop dirty_bitmaps_loaded state variable
  block/qcow2: improve error message in qcow2_inactivate
  iotests: 169: drop deprecated 'autoload' parameter
  qapi: add transaction support for x-block-dirty-bitmap-merge
  blockdev: rename block-dirty-bitmap-clear transaction handlers
  dirty-bitmap: make it possible to restore bitmap after merge
  dirty-bitmap: rename bdrv_undo_clear_dirty_bitmap
  dirty-bitmap: switch assert-fails to errors in bdrv_merge_dirty_bitmap
  blockdev-backup: add bitmap argument

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