llvmPackages_20.llvm: fix test failure on riscv64

      ++

        lib.optional (lib.versionAtLeast release_version "15")

          # Just like the `llvm-lit-cfg` patch, but for `polly`.

          (getVersionFile "llvm/polly-lit-cfg-add-libs-to-dylib-path.patch");

          (getVersionFile "llvm/polly-lit-cfg-add-libs-to-dylib-path.patch")

      ++

        lib.optional (lib.versions.major release_version == "20" && stdenv.hostPlatform.isRiscV)

          # Test failure on riscv64, fixed in llvm 21

          # https://github.com/llvm/llvm-project/issues/150818

          (

            fetchpatch {

              url = "https://github.com/llvm/llvm-project/commit/bd49bbaaafc98433a2cb4e95ce25b7a201baf5a5.patch";

              hash = "sha256-3hkbYPUVRAtWpo5qBmc2jLZLivURMx8T0GQomvNZesc=";

              stripLen = 1;

            }

          );

    nativeBuildInputs = [

      cmake