Add default virtual destructor to test RefObject.
Add default virtual destructor to test RefObject.

Fixes https://github.com/google/iree/issues/3451

PiperOrigin-RevId: 336979388

google/iree,google/iree,iree-org/iree,google/iree,iree-org/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,google/iree,iree-org/iree,iree-org/iree,google/iree,google/iree