chore(3p): update NixOS channels to 2021-08-30 r/2801

This lets us benefit from the recent OpenSSL security-related
update [1]. Since nixos-unstable is still stuck, we temporarily
use nixos-unstable-small as our unstable channel.

Fixes necessary:

* //users/sterni/nix/char:
  Someone has decided to drop writers.writeC upstream [2],
  so we reimplement it ad-hoc using runCommandCC

[1]: https://www.openssl.org/news/secadv/20210824.txt
[2]: https://github.com/nixos/nixpkgs/commit/982f46985e37a6488d8e904b46e0cba2060adc71

Change-Id: Id84756e2e370296b7a27e1a3f1744f58f8fe3c47
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3463
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

0 files changed, 0 insertions, 0 deletions