RefCount: Fix reference counting pointer == and != with a T* on the left.

RefCount: Fix reference counting pointer == and != with a T* on the left.

These operators were expecting a const T& instead of a const T*, and were not
being picked up and used by gcc in the right places as a result. Apparently no
one used these operators before. A unit test which exposed these problems,
verified the solution, and checks other basic functionality is on the way.