bpo-27961: Replace PY_ULLONG_MAX with ULLONG_MAX (GH-17539)

Author: sir-sigurd

Doc/c-api/long.rst

@@ -304,7 +304,7 @@ distinguished from a number.  Use :c:func:`PyErr_Occurred` to disambiguate.
    it to a :c:type:`PyLongObject`.
 
    If the value of *obj* is out of range for an :c:type:`unsigned long long`,
-   return the reduction of that value modulo ``PY_ULLONG_MAX + 1``.
+   return the reduction of that value modulo ``ULLONG_MAX + 1``.
 
    Returns ``(unsigned long long)-1`` on error.  Use :c:func:`PyErr_Occurred`
    to disambiguate.