Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20171122' into staging

migration/next for 20171122

# gpg: Signature made Wed 22 Nov 2017 08:43:13 GMT
# gpg:                using RSA key 0xF487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>"
# gpg:                 aka "Juan Quintela <quintela@trasno.org>"
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* remotes/juanquintela/tags/migration/20171122:
  migration/ram.c: do not set 'postcopy_running' in POSTCOPY_INCOMING_END
  migration, xen: Fix block image lock issue on live migration

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