Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

# gpg: Signature made Wed Jun 24 16:27:53 2015 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/block-pull-request:
  virito-blk: drop duplicate check
  qemu-iotests: fix 051.out after qdev error message change
  iov: don't touch iov in iov_send_recv()
  raw-posix: Introduce hdev_is_sg()
  raw-posix: Use DPRINTF for DEBUG_FLOPPY
  raw-posix: DPRINTF instead of DEBUG_BLOCK_PRINT
  Fix migration in case of scsi-generic
  block: Use bdrv_is_sg() everywhere
  nvme: Fix memleak in nvme_dma_read_prp
  vvfat: add a label option
  util/hbitmap: Add an API to reset all set bits in hbitmap
  virtio-blk: Use blk_drain() to drain IO requests
  block-backend: Introduce blk_drain()
  throttle: Check current timers before updating any_timer_armed[]
  block: Let bdrv_drain_all() to call aio_poll() for each AioContext

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