coverity: Incorrect shifting in DNS_RPZ_ZMASK

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*** CID 1430160:    (BAD_SHIFT)
/lib/ns/query.c: 2610 in rpz_get_zbits()
2604             *      the smallest name,
2605             *      the longest IP address prefix,
2606             *      the lexically smallest address.
2607             */
2608            if (st->m.policy != DNS_RPZ_POLICY_MISS) {
2609                    if (st->m.type >= rpz_type) {
>>>     CID 1430160:    (BAD_SHIFT)
>>>     In expression "1 << st->m.rpz->num + 1", left shifting by more than 31 bits has undefined behavior.  The shift amount, "st->m.rpz->num + 1", is as much as 63.
2610                            zbits &= DNS_RPZ_ZMASK(st->m.rpz->num);
2611                    } else{
2612                            zbits &= DNS_RPZ_ZMASK(st->m.rpz->num) >> 1;
2613                    }
2614            }
2615
/lib/ns/query.c: 2612 in rpz_get_zbits()
2606             *	the lexically smallest address.
2607             */
2608            if (st->m.policy != DNS_RPZ_POLICY_MISS) {
2609                    if (st->m.type >= rpz_type) {
2610                            zbits &= DNS_RPZ_ZMASK(st->m.rpz->num);
2611                    } else{
>>>     CID 1430160:    (BAD_SHIFT)
>>>     In expression "1 << st->m.rpz->num + 1", left shifting by more than 31 bits has undefined behavior.  The shift amount, "st->m.rpz->num + 1", is as much as 63.
2612                            zbits &= DNS_RPZ_ZMASK(st->m.rpz->num) >> 1;
2613                    }
2614            }
2615
2616            /*
2617             * If the client wants recursion, allow only compatible policies.