Default-enable `llvm_tools_enabled` when no `config.toml` is present Fixes #133195. cc `@wesleywiser` could you double check if with this patch and no `config.toml` that you can run `./x test tests/ui --stage 1`? `llvm-objcopy` is usually required by cg_ssa on macOS to workaround bad `strip`s. cc `@bjorn3` I hope this doesn't break cg_clif... r? bootstrap