Pass GN header visibility check. Updates angle_util to see the loader includes even if the loader is not enabled. This makes the GN check happy. Bug: angleproject:3052 Change-Id: Ifd23070385beefede4358c7b4c1823dc87b5ded8 Reviewed-on: https://chromium-review.googlesource.com/c/1395809 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>