Merge remote-tracking branch 'remotes/amit-migration/tags/migration-for-2.6-6' into staging

migration:
* add avx2 instruction optimization, speeds up zero-page checking on
  compatible architectures and compilers (gcc 4.9+)
* add additional postcopy stats to 'info migrate' output

# gpg: Signature made Tue 08 Mar 2016 11:29:48 GMT using RSA key ID 854083B6
# gpg: Good signature from "Amit Shah <amit@amitshah.net>"
# gpg:                 aka "Amit Shah <amit@kernel.org>"
# gpg:                 aka "Amit Shah <amitshah@gmx.net>"

* remotes/amit-migration/tags/migration-for-2.6-6:
  cutils: add avx2 instruction optimization
  configure: detect ifunc and avx2 attribute
  Postcopy: Fix sync count in info migrate

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