cgpt: sanitize features field

Make sure we don't let people add unknown features (like typos).

BUG=chromium:644845
TEST=precq passes

Change-Id: Iebd7ca8719d56c63b5fc301e8c7355b2fc1453c9
Reviewed-on: https://chromium-review.googlesource.com/382811
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
1 file changed