buildgcc: Don't use BUILDDIRPREFIX

Change-Id: I7be9b39a0d92882fa437f666d7f4a85e6f0a23f6
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10489
Tested-by: build bot (Jenkins)
Reviewed-by: Alexander Couzens <lynxis@fe80.eu>
1 file changed