Merge remote-tracking branch 'remotes/cohuck/tags/s390x-20160816' into staging

Build fix for the ccw bios (bios itself not rebuilt).

# gpg: Signature made Tue 16 Aug 2016 08:00:16 BST
# gpg:                using RSA key 0xDECF6B93C6F02FAF
# gpg: Good signature from "Cornelia Huck <[email protected]>"
# gpg:                 aka "Cornelia Huck <[email protected]>"
# Primary key fingerprint: C3D0 D66D C362 4FF6 A8C0  18CE DECF 6B93 C6F0 2FAF

* remotes/cohuck/tags/s390x-20160816:
  pc-bios/s390-ccw.img: Fix build

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