Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20180724a' into staging

Migration pull for 3.0

Fixes only

# gpg: Signature made Tue 24 Jul 2018 19:31:39 BST
# gpg:                using RSA key 0516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>"
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20180724a:
  migration: fix duplicate initialization for expected_downtime and cleanup_bh
  tests: only update last_byte when at the edge
  migration: disallow recovery for release-ram
  migration: update recv bitmap only on dest vm
  audio/hda: Fix migration
  migrate: Fix cancelling state warning
  migration: fix potential overflow in multifd send

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