[c-nsp] "snmpEngineTime" seems to wrap with "sysUpTime" in old IOS release

[Nathan Lannine]

> How to explain this behavior? Is it likely some kind of SNMP agent

I may not have this totally right, but I believe sysUpTime is a 32-bit
value, which will only go out about 400 and some odd days before it
wraps to 0.