GeezerVison

Fixes mypyc/mypyc#1253

The tp_hash slot of a native class converted the value returned by __hash__ with CPyTagged_AsSsize_t(), so an int that doesn't fit in Py_hash_t made hash() raise OverflowError. CPython's slot_tp_hash, which a class defined in Python uses, accepts any int and hashes one that doesn't fit again with int.__hash__.

generate_hash_wrapper() now does the same:

• A short int is still handled inline, with -1 changed to -2 as before.
• A long int goes through the new CPy_HashFromResult() in generic_ops.c, which does what slot_tp_hash
  does with the result: an int that fits in Py_hash_t is used as is, a larger one is hashed again, and
  anything that isn't an int raises TypeError: __hash__ method should return an integer.
• Other return types are boxed if needed and passed to CPy_HashFromResult(). With -> Any, a result that
  isn't an int used to raise TypeError: an integer is required. A __hash__ declared to return a native int
  type such as i64 segfaulted (or raised SystemError if it returned 0), because the slot passed the C value
  to PyLong_AsSsize_t() as an object pointer.

The new run test testDundersHashResult covers -> int and -> Any with values that fit in Py_hash_t, -1, values that don't fit, a long int that fits only on 64-bit platforms (2**62), True and results that aren't ints, plus an -> i64 method that returns -1. The expected results are the same on 32-bit platforms.