CF: don't build swift-corefoundation anymore on Hydra

[FRidh]

It fails almost every time. Sometimes, after a restart it does build but
not always. To reduce the noise from this failure and all its reverse
dependencies, let's not build it anymore on Hydra.

#72146

Motivation for this change

cc @NixOS/darwin-maintainers @vcunat

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• 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 nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @

[vcunat]

Note: on 19.09 it's probably bearable (rarely needs to rebuild), but for staging(-next) work it's a real problem.

[vcunat]

BUT, I don't think this PR helps as-is. The problem of the breakage is that so many packages depend on this package ATM.

[vcunat]

And the ticket with most information on is #66811

[LnL7]

CoreFoundation is part of the stdenv so this is kind of pointless. I'm not sure how to debug it further, almost seems like a compiler bug. The only workaround I can think of at the moment is retrying the build phase similar to my reproduction snippet, but that's pretty horrible 😕.

[vcunat]

OK, discussion can continue on that open ticket.