[reclient] Add option for remote links.

The configuration file is _not_ production ready, as the docker
container image is likely larger than needed - so using remote
links is not yet production ready. But the functionality technicaly
works, and remote links are required for some other applications in the
future, such as not downloading intermediates.

Note that it adding nacl link support shouldn't be much extra work from
now (I expect a new config file is all we need), but it's not work
that seems worth doing ATM.

I also took the chance to trim down hardcoded inputs a bit more, except
for the introduced links where we do need some of those assets (eg ldd).

Change-Id: I8e1d36ce2f7099ab2ffad3bc611dc02111f975e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2910712
Auto-Submit: Rubens Farias <rubensf@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/master@{#885618}
NOKEYCHECK=True
GitOrigin-RevId: a3b279a04129cd52500afd1df3ce98d9a29d1181
3 files changed