Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-migration-20210609a...

Migration pull for 2021-06-09

Yank crash fix from Leo
RDMA fix from Li
mptcp support from me
dirty-rate changes from Hyman and Peter

(Note I've switched to the gitlab I've been using for virtiofs pulls)

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
# gpg: Signature made Wed 09 Jun 2021 15:40:01 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-gitlab/tags/pull-migration-20210609a:
  hmp: Add "calc_dirty_rate" and "info dirty_rate" cmds
  migration/dirtyrate: make sample page count configurable
  sockets: Support multipath TCP
  migration/socket: Close the listener at the end
  migration: Add cleanup hook for inwards migration
  io/net-listener: Call the notifier during finalize
  channel-socket: Only set CLOEXEC if we have space for fds
  migration/rdma: Fix cm event use after free
  yank: Unregister function when using TLS migration

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