Merge remote-tracking branch 'kwolf/for-anthony' into staging

# By Kevin Wolf (6) and Stefan Hajnoczi (2)
# Via Kevin Wolf
* kwolf/for-anthony:
  ahci: Fix FLUSH command
  migration: Fail migration on bdrv_flush_all() error
  cpus: Add return value for vm_stop()
  block: Add return value for bdrv_flush_all()
  qemu-iotests: Update 051 reference output
  block: Don't parse protocol from file.filename
  block: add drive_backup HMP command
  blockdev: add sync mode to drive-backup QMP command

Message-id: 1373887000-4488-1-git-send-email-kwolf@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>