Merge remote-tracking branch 'stefanha/block' into staging

Merge remote-tracking branch 'stefanha/block' into staging

* stefanha/block:
  rbd: add an asynchronous flush
  iotests: Add 'check -ssh' option to test Secure Shell block device.
  block: ssh: Use libssh2_sftp_fsync (if supported by libssh2) to flush to disk.
  block: Add support for Secure Shell (ssh) block device.
  ide: refuse WIN_READ_NATIVE_MAX on empty device
  qemu-iotests: filter QEMU_PROG in 051.out
  qemu-iotests: Add test for -drive options
  qemu-iotests: A few more bdrv_pread/pwrite tests
  block: Introduce bdrv_pwritev() for qcow2_save_vmstate
  savevm: Implement block_writev_buffer()
  block: Introduce bdrv_writev_vmstate

Conflicts:
	savevm.c

aliguori: add f->pos parameter to writev_buffer().

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>