bpo-1617161: Make the hash and equality of methods not depending on the value of self. (GH-7848)

* The hash of BuiltinMethodType instances no longer depends on the hash
  of __self__. It depends now on the hash of id(__self__).
* The hash and equality of ModuleType and MethodWrapperType instances no
  longer depend on the hash and equality of __self__. They depend now on
  the hash and equality of id(__self__).
* MethodWrapperType instances no longer support ordering.