hterm: add concat/hterm_all.concat

Change-Id: Icb084f2947b11fed84c35d50e0dcf5578b6d7a70
Reviewed-on: https://chromium-review.googlesource.com/209388
Reviewed-by: Robert Ginda <rginda@chromium.org>
Tested-by: Robert Ginda <rginda@chromium.org>