Make xrange more Py_ssize_t aware, by assuming a Py_ssize_t is always at

least as big as a long. I believe this to be a safe assumption that is being
made in many parts of CPython, but a check could be added.

len(xrange(sys.maxint)) works now, so fix the testsuite's odd exception for
64-bit platforms too. It also fixes 'zip(xrange(sys.maxint), it)' as a
portable-ish (if expensive) alternative to enumerate(it); since zip() now
calls len(), this was breaking on (real) 64-bit platforms. No additional
test was added for that behaviour.

Objects/rangeobject.c

@@ -104,13 +104,6 @@ range_item(rangeobject *r, Py_ssize_t i)
 static Py_ssize_t
 range_length(rangeobject *r)
 {
-#if LONG_MAX != INT_MAX /* XXX ssize_t_max */
-	if (r->len > INT_MAX) {
-		PyErr_SetString(PyExc_ValueError,
-				"xrange object size cannot be reported");
-		return -1;
-	}
-#endif
 	return (Py_ssize_t)(r->len);
 }