llvmPackages: clean up rebuild avoidance

      # This is an "oddly ordered" bootstrap just for Darwin. Probably

      # don't want it otherwise.

      clangNoCompilerRtWithLibc =

        wrapCCWith rec {

      clangNoCompilerRtWithLibc = wrapCCWith rec {

        cc = tools.clang-unwrapped;

        libcxx = null;

        bintools = bintools';

        extraPackages = [ ];

        extraBuildCommands = mkExtraBuildCommands0 cc;

        }

        # FIXME: This should be inside the `wrapCCWith` call.

        // lib.optionalAttrs stdenv.targetPlatform.isWasm {

          nixSupport.cc-cflags = [ "-fno-exceptions" ];

        nixSupport.cc-cflags = lib.optional stdenv.targetPlatform.isWasm "-fno-exceptions";

      };

      # Aliases