Write them per-board and merge them after everything is done. This prepares for build parallelization. Change-Id: Ia4e7ce03473bcf8861fb9ae06e9c1270292401ac Signed-off-by: Patrick Georgi <patrick@georgi-clan.de> Reviewed-on: http://review.coreboot.org/407 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>