Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20170628' into...

migration/next for 20170628

# gpg: Signature made Wed 28 Jun 2017 12:16:44 BST
# gpg:                using RSA key 0xF487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>"
# gpg:                 aka "Juan Quintela <quintela@trasno.org>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* remotes/juanquintela/tags/migration/20170628:
  exec: fix access to ram_list.dirty_memory when sync dirty bitmap
  migration: add "return-path" capability
  vmstate: error hint for failed equal checks
  migration: add comment for TYPE_MIGRATE
  migration: hmp: dump globals
  migration: merge enforce_config_section somewhat
  migration: move skip_section_footers
  migration: move skip_configuration out
  migration: move only_migratable to MigrationState
  migration: move global_state.optional out
  migration: let MigrationState be a qdev
  vl: clean up global property registration
  accel: introduce AccelClass.global_props
  machine: export register_compat_prop()

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