chore(gs/achilles): Integrate with the depot build r/2291

Get achilles building in Nix as part of the depot's build tree. This
involved making it work with stable rust, since the depot only exposes
stable rust to sub-packages, which turned out to be fairly
straightforward.

Also adds libffi as a new top-level expose, since it's required to build achilles

Change-Id: I5f6dedb26c0b81ec258aedde1973e74903c07ece
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2612
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

0 files changed, 0 insertions, 0 deletions