This allows for having some global comments such as timezones or
long-term unavailability.

The comments go into build/OWNERS.status (that way, they should be
available in all repos that map in build/ for the gn config files).
The local can be overwritten in codereview.settings.

The format is

email: status

Comments (starting with #) are allowed in that file, but they're ignored.

BUG=694222
R=dpranke@chromium.org

Change-Id: I49f58be87497d1ccaaa74f0a2f3d373403be44e7
Reviewed-on: https://chromium-review.googlesource.com/459542
Commit-Queue: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>