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/1395809Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>