Support building seabios

SEABIOS will not correctly build without this patch.
I'm not quite sure how it ever built, but it perhaps
is because of changes in gcc.

BUG=chrome-os-partner:9059
TEST=emerge a firmware image using seabios
emerge-lumpy sys-boot/chromeos-coreboot sys-boot/chromeos-seabios
sys-boot/chromeos-bootimage

It will no longer fail.

Change-Id: I6cb3c5bc268938d64d3083d0de35ab0c0e8e9cce
1 file changed