build_image: Add DLC installation hook

Invoke the build_dlc to install all the DLCs in "dlc" directory of the
output directory. This script does nothing if the directory containing
the DLC builds does not exist, so it should play nice with builds that
do not yet build DLCs.

BUG=chromium:887158
TEST=build_image; dummy-dlc were copied properly.
CQ-DEPEND=CL:1433192

Change-Id: I3c7c558ef0e02ae8c840024821ec6c675ebfc10c
Reviewed-on: https://chromium-review.googlesource.com/1252563
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
1 file changed