Merge remote-tracking branch 'remotes/juanquintela/tags/migration/20151203' into staging

migration/next for 20151203

# gpg: Signature made Wed 02 Dec 2015 23:19:10 GMT using RSA key ID 5872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>"
# gpg:                 aka "Juan Quintela <quintela@trasno.org>"

* remotes/juanquintela/tags/migration/20151203:
  migration: do floating-point division
  migration: Clean up use of g_poll() in socket_writev_buffer()

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