print_varbind: Use the correct OID size for OIDs

[ernie]

Looks like some code is still reading varbinds as long regardless of type. Apologies for not including a test, but the test harness keeps segfaulting for me on my machine.

[ernie]

Incidentally, stumbled upon this while trying to track down some way to get named number lists to translate to their names. Given, for instance:

ltmPoolStatusAvailState OBJECT-TYPE 
    SYNTAX INTEGER {
        none(0),
        green(1),
        yellow(2),
        red(3),
        blue(4),
        grey(5)
    }
    MAX-ACCESS read-only
    STATUS current
    DESCRIPTION
        "The availability of the specified pool indicated in color.
        none - error;
        green - available in some capacity;
        yellow - not currently available;
        red - not available;
        blue - availability is unknown;
        gray - unlicensed"
    ::= { ltmPoolStatusEntry 2 } 

I can only retrieve an integer value from the varbind, but Net-SNMP's snmpget returns:

F5-BIGIP-LOCAL-MIB::ltmPoolStatusAvailState."a_string" = INTEGER: green(1)