add Kbuild support to abuild and enable it per default;

add Kbuild support to abuild and enable it per default;
use -o/--oldconfig to get the old behavior (and use that
option in kbuildall to get the old config)

I changed the qa.coreboot.org autobuild system to use -o
for now so we get build reports from the old and new config,
still.

Signed-off-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Myles Watson <mylesgw@gmail.com>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5066 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1