Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20200507a' into...

Migration pull 2020-05-07

Mostly tidy-ups, but two new features:
  cpu-throttle-tailslow for making a gentler throttle
  xbzrle encoding rate measurement for getting a feal for xbzrle
performance.

# gpg: Signature made Thu 07 May 2020 18:00:27 BST
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20200507a:
  migration/multifd: Do error_free after migrate_set_error to avoid memleaks
  migration/multifd: fix memleaks in multifd_new_send_channel_async
  migration/xbzrle: add encoding rate
  migration/rdma: fix a memleak on error path in rdma_start_incoming_migration
  migration/ram: Consolidate variable reset after placement in ram_load_postcopy()
  migration/throttle: Add cpu-throttle-tailslow migration parameter
  migration/colo: Add missing error-propagation code
  docs/devel/migration: start a debugging section
  migration: move the units of migrate parameters from milliseconds to ms
  monitor/hmp-cmds: add hmp_handle_error() for hmp_migrate_set_speed()
  migration/migration: improve error reporting for migrate parameters
  migration: fix bad indentation in error_report()

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