Checking in the code for PEP 357.

This was mostly written by Travis Oliphant.
I've inspected it all; Neal Norwitz and MvL have also looked at it
(in an earlier incarnation).

Objects/intobject.c

@@ -1069,6 +1069,7 @@ static PyNumberMethods int_as_number = {
 	int_true_divide,	/* nb_true_divide */
 	0,			/* nb_inplace_floor_divide */
 	0,			/* nb_inplace_true_divide */
+	(lenfunc)PyInt_AsSsize_t, /* nb_index */
 };
 
 PyTypeObject PyInt_Type = {