steam-chrootenv: add iana-etc, fixes #25443

[DIzFer]

Motivation for this change

Both Borderlands 2 and Borderlands: The Pre-Sequel silently crash when downloading hotfixes, as documented in #25443. This appears to be the same bug as flathub/com.valvesoftware.Steam#5, which is fixed by having a populated /etc/services.

Things done

Adding iana-etc to the chrootenv's environment makes this crash go away. I may again be messing up where the package should be added...

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

---

[lukateras]

Thank you! We might soon hit nearly 100% compatibility with Steam games in this pace :-)

[lukateras]

I've just rebuilt steam-run with this change and I can verify that after this change /etc/services is properly populated, and that it wasn't before. I don't have Borderlands 2, but I plan to buy it soon, I'll test it then. Again, thanks <3