message: activate pre_validation when llvm backend selected
diff: @@ -263,7 +263,7 @@ impl<
  fn requires_pre_validation(backend: Backend) -> bool {
  match backend {
  Backend::Cranelift => true,
  - Backend::LLVM => false,
  + Backend::LLVM => true,
  Backend::Singlepass => false,
  }
  }
  