llvmPackages_{12,13,14,15,16,17,18,git}: use common libunwind

[RossComputerGuy]

Description of changes

Partial split from #299807

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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.

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[Ericson2314]

Why is it (hasPatches || lib.versionOlder release_version "18") and not just hasPatches? I don't see what is special about LLVM 18 still.

[RossComputerGuy]

@Ericson2314 Without it, it causes a rebuild.

[RossComputerGuy]

https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/compilers/llvm/17/libunwind/default.nix vs https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/compilers/llvm/18/libunwind/default.nix

LLVM 18 removes those hooks, 17 has them despite not having any patches. If we were to include the hooks only when there are patches then LLVM 17 will rebuild. We don't want rebuilds.

[Ericson2314]

@RossComputerGuy OK great thanks! We can do that in a follow-up PR then.