bios: recompile BIOS

SeaBIOS is really close to spilling over to 256k.  Until we can better
handle migration across RAM block size changes, recompile SeaBIOS with
a compiler that causes the binary to still fit in 128k.

This was built with:

gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) (GCC)

On 64-bit Fedora 18.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>