Merge remote-tracking branch 'remotes/kraxel/tags/pull-ipxe-20150903-1' into staging

ipxe: update to 35c53797 to 4e03af8, build tweaks.

# gpg: Signature made Thu 03 Sep 2015 13:52:01 BST using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"

* remotes/kraxel/tags/pull-ipxe-20150903-1:
  ipxe: update binaries
  ipxe: use upstream configuration
  ipxe: don't override GITVERSION
  ipxe: update from 35c53797 to 4e03af8

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