IPFIX and v9 data templates: Element IDs 52 and 53

The IPv4, IPv6, MPLS-IPv4, and MPLS-IPv6 templates within the IPFIX and Version 9 data templates now contain two elements that hold the minimum TTL value (ID 52) and the maximum TTL value (ID 53) for the sampled packet. Because the system does not maintain a flow cache, the minimum and maximum TTL values are the same. For the ingress direction of sampling, the TTL value received on the wire is the value reported in the export records. For egress direction of sampling, the TTL value transmitted in the forwarded packet is the value reported in the export records.