Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20180323a' into...

Merge remote-tracking branch 'remotes/dgilbert/tags/pull-migration-20180323a' into staging

Migration fixes for 2.12

All small fixes.  Dan's is a missing piece
of a cleanup that finally completes something,
and between Paolo, Dan and myself we recon it's
still on the edge of being a bug fix.

# gpg: Signature made Fri 23 Mar 2018 20:17:40 GMT
# gpg:                using RSA key 0516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>"
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert/tags/pull-migration-20180323a:
  migration: Fix block migration flag case
  migration/block: compare only read blocks against the rate limiter
  migration/block: limit the number of parallel I/O requests
  migration: Fix rate limiting issue on RDMA migration
  migration: convert socket server to QIONetListener

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