Add clif-util compile option to output object file (#5493)

* add clif-util compile option to output object file

* switch from a box to a borrow

* update objectmodule tests to use borrowed isa

* put targetisa into an arc

cranelift/codegen/src/isa/s390x/mod.rs

@@ -191,7 +191,7 @@ pub fn isa_builder(triple: Triple) -> IsaBuilder {
         constructor: |triple, shared_flags, builder| {
             let isa_flags = s390x_settings::Flags::new(&shared_flags, builder);
             let backend = S390xBackend::new_with_flags(triple, shared_flags, isa_flags);
-            Ok(Box::new(backend))
+            Ok(backend.wrapped())
         },
     }
 }