try native toolchain on darwin

Author: facundominguez

shell.nix

@@ -13,7 +13,7 @@ mkShell {
   LANG="C.UTF-8";
 
   buildInputs = [
-    bazel_7
+    bazel_6
     git
     gnused
     nix
@@ -26,6 +26,8 @@ mkShell {
     glibcLocales
     # to avoid CA certificate failures on macOS CI
     cacert
+  ] ++ lib.optionals stdenv.hostPlatform.isDarwin [
+    darwin.cctools
   ];
 
   shellHook = ''