build_image: Enable license credits file creation for base image.

After emerging the packages onto our base image, create the license
credits file for those packages and store it on the rootfs.

BUG=chromium:197970 chromium:356543
TEST=Ran build image, and examined the results.

Change-Id: I2f9dc554072874bef879f31cca539b81ee064443
Tested-by: Don Garrett <>
Reviewed-by: Mike Frysinger <>
Commit-Queue: Don Garrett <>
1 file changed