build_stages: pass the list of packages to build to build_packages

build_packages automatically determines a list of packages to build if
none is given. This applies to most of the configs in cbuidlbot.

This CL moves the logic into cbuildbot so that we explicitly pass a
list of packages to build_packages. This way, we also know what
packages to extract the dependencies for later.

BUG=chromium:422639
TEST=`cbuildbot --remote link-paladin`

Change-Id: I025c771f66cfc57a2fc0cf390e93dc373952d4d8
Reviewed-on: https://chromium-review.googlesource.com/225781
Tested-by: Yu-Ju Hong <yjhong@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Yu-Ju Hong <yjhong@chromium.org>
1 file changed