cbuildbot scripts: Add an builder_path entry to /etc/lsb_release file on the
DUT.

Current image's /etc/lsb-release file does not include the whole image name.
For example, it only contains board (lumpy), version (8667.0.0), and milstone
(54), which cannot be used to create a recognizable image name, like
lumpy-paladin/R54-8667.0.0, for devserver to download its packages.

This CL add this info as CHROMEOS_RELEASE_BUILDER_PATH to the /etc/lsb-release
file of any built images.

BUG=chromium:634642
TEST=trybot success.
https://uberchromegw.corp.google.com/i/chromiumos.tryserver/builders/
paladin/builds/1290.
Run build_image locally without/with builder_path entry.
CQ-DEPEND=CL:366130

Change-Id: I9a80a5137cf567bdf63845a9182e1191f5b82d97
Reviewed-on: https://chromium-review.googlesource.com/366056
Commit-Ready: Xixuan Wu <xixuan@chromium.org>
Tested-by: Xixuan Wu <xixuan@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
2 files changed