Use --link-dest instead of --copy-dest to save temp space during the update.

BUG=chrome-os-partner:14293
TEST=Manual

Change-Id: I5c39985a6ba88e2c5a513ac56ff0f352cb216509
Reviewed-on: https://gerrit.chromium.org/gerrit/33604
Reviewed-by: Hsinyu Chao <hychao@chromium.org>
Tested-by: Hsinyu Chao <hychao@chromium.org>
1 file changed