[autotest] pin chromiumos projects to 'prod'.

We use several chromiumous projects along with autotest in the lab. Like
the autotest repo, we now pin these other repos also to a 'prod' branch.

BUG=chromium:463275
TEST=Run build_externals on a ganeti instance, ensure that that all the
     git repos pulled are at the expected git-sha#

Change-Id: I112b6581b62acd7714f49bb01efd12a9c912f6f6
Reviewed-on: https://chromium-review.googlesource.com/264155
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
1 file changed