cc-wrapper: Workaround gnuabielfv{1,2} support deficiency on Clang

[OPNA2608]

Description of changes

Clang doesn't parse the "gnuabielfv{1,2}" part of the triplet as anything beyond "gnu", so desired ABI gets ignored.

Work around this by explicitly setting the ABI.

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Follow-up to #307819 which fixes building LLVM on powerpc64, this gets llvmPackages*.stdenv working.

• I haven't checked how this may affect musl, and
• I'm not sure if checking for non-"gnu" has any point beyond signaling intention, because we assert on powerpc64{,le}-unknown-linux-gnu due to this exact ABI ambiguity. Maybe checking for non-"musl" would be better, since that only supports ELFv2?

Staging just so cc-wrapper stuff that might get sent there doesn't encounter any merge conflicts.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • powerpc64-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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