scalar int hashing broken on 64 bit python3 #3793

In [1]: import numpy as np;
In [2]: i=2**31;
In [3]: print(np.int64(i) in {i:111})
False
In [6]: print(hash(np.int64(i)), hash(i))
(-2147483648, 2147483648)

on python2 it returns True,
discovered on s390x where hash(np.int64(4) returns zero because int_arrtype_hash casts the object to PyIntScalarObject which cuts of four bytes (as its really PyLongScalarObject) which are zero on big endian:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=724047

This is probably also the cause of the difference on amd64.

most likely also the cause scipy/scipy#2930