lld: build with 2M stack size on musl

[alyssais]

Description of changes

Port of 6485a02 ("llvm 14 lld: build with 2M stack size to fix firefox lto").

LLVM 7 doesn't build for Musl for unrelated reasons, as it segfaults during a test. I gave up trying to fix it when I realised it doesn't do that if I enableDebugging.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.05 Release Notes (or backporting 22.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[sternenseemann]

Commit message should read lld though, maybe indicate somehow that it is about all available versions.

[alyssais]

maybe indicate somehow that it is about all available versions.

I think we should get into the habit of being surprised when an LLVM change is not applied to all versions, not when it is.

[rrbutani]

Subjective (and something I should have raised on the original PR or in the LLVM 15 PR) so feel free to ignore:

I'd really appreciate a comment here explaining why this is necessary (perhaps with a link to this (and maybe this/this) and a short snippet saying that the pkgsMusl.firefox needs this -- or even just a link to #191372).

IMO it's a little hard to infer why this is needed from the surrounding context and while all the details are definitely still available in PR comments/commit messages, with our "copy the previous llvmPackages's files" flow it takes a bit of effort to map back to the original commit (though I guess having llvmPackages_git and keeping it up to date remedies this, somewhat).

[alyssais]

I'd really appreciate a comment here explaining why this is necessary (perhaps with a link to this (and maybe this/this) and a short snippet saying that the pkgsMusl.firefox needs this -- or even just a link to #191372).

Done. I explained inline rather than linking though, because links rot.