Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20170906a' into...

migration pull 2017-09-06

# gpg: Signature made Wed 06 Sep 2017 19:39:23 BST
# gpg:                using RSA key 0x0516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20170906a:
  migration: dump str in migrate_set_state trace
  snapshot/tests: Try loadvm twice
  migration: Reset rather than destroy main_thread_load_event
  runstate/migrate: Two more transitions
  host-utils: Simplify pow2ceil()
  host-utils: Proactively fix pow2floor(), switch to unsigned
  xbzrle: Drop unused cache_resize()
  migration: Report when bdrv_inactivate_all fails

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