rocmPackages.clang: enable structured attrs

This fixes the build with the new debuginfo changes.

pkgs/development/rocm-modules/6/llvm/default.nix

@@ -348,6 +348,8 @@ rec {
           };
           # Ensure we don't leak refs to compiler that was used to bootstrap this LLVM
           disallowedReferences = (old.disallowedReferences or [ ]) ++ disallowedRefsForToolchain;
+          # Enable structured attrs for separateDebugInfo, because it is required with disallowedReferences set
+          __structuredAttrs = true;
           requiredSystemFeatures = (old.requiredSystemFeatures or [ ]) ++ [ "big-parallel" ];
           # https://github.com/llvm/llvm-project/blob/6976deebafa8e7de993ce159aa6b82c0e7089313/clang/cmake/caches/DistributionExample-stage2.cmake#L9-L11
           cmakeFlags =