Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20170531' into...

Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20170531' into staging

migration/next for 20170531

# gpg: Signature made Wed 31 May 2017 08:53:06 BST
# gpg:                using RSA key 0xF487EF185872D723
# gpg: Good signature from "Juan Quintela <[email protected]>"
# gpg:                 aka "Juan Quintela <[email protected]>"
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03  4B82 F487 EF18 5872 D723

* remotes/juanquintela/tags/migration/20170531:
  migration: use dirty_rate_high_cnt more aggressively
  migration: set bytes_xfer_* outside of autoconverge logic
  migration: set dirty_pages_rate before autoconverge logic
  migration: keep bytes_xfer_prev init'd to zero
  migration: Create savevm.h for functions exported from savevm.c

Signed-off-by: Peter Maydell <[email protected]>