Make sure PolyBoRi hashes return Py_ssize_t
Merge branch 'u/jdemeyer/ticket/15755' of git://trac.sagemath.org/sage into ticket/15755
32-bit fix for hashes
Trac #15863: 32-bit hash fix for Cython update

This fixes a hash failure due to the Cython upgrade #15755

Note: I'm curently not testing every ticket on 32-bit since we don't
have a buildslave that can do it in a reasonable amount of time.

URL: http://trac.sagemath.org/15863
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): Jeroen Demeyer