Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20151119' into...

migration/next for 20151119

# gpg: Signature made Thu 19 Nov 2015 11:17:07 GMT using RSA key ID 5872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>"
# gpg:                 aka "Juan Quintela <quintela@trasno.org>"

* remotes/juanquintela/tags/migration/20151119:
  migration: normalize locking in migration/savevm.c
  migration: implement bdrv_all_find_vmstate_bs helper
  migration: reorder processing in hmp_savevm
  snapshot: create bdrv_all_create_snapshot helper
  migration: drop find_vmstate_bs check in hmp_delvm
  snapshot: create bdrv_all_find_snapshot helper
  migration: factor our snapshottability check in load_vmstate
  snapshot: create bdrv_all_goto_snapshot helper
  snapshot: create bdrv_all_delete_snapshot helper
  snapshot: return error code from bdrv_snapshot_delete_by_id_or_name
  snapshot: create helper to test that block drivers supports snapshots
  Unneeded NULL check
  migration: Dead assignment of current_time
  Set last_sent_block

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