When generating os-release also add version/build IDs

BUG=b:27841076
TEST=image build and /etc/os-release has expected these fields set
CQ-DEPEND=CL:342485, CL:343549

Change-Id: I03cd43e1aaefa6f4f039d5efb08c51294a164b39
Reviewed-on: https://chromium-review.googlesource.com/342574
Commit-Ready: Andrey Ulanov <andreyu@google.com>
Tested-by: Andrey Ulanov <andreyu@google.com>
Reviewed-by: Ilja H. Friedel <ihf@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed