Those are intended for the in-tree /usr/sbin/snmpd, not for Net-SNMP.
Depends what you're monitoring, but base snmpd is sufficient for many
Most of these can and should be rewritten to use the sysctl interfaces
added in 4.3, this may also fix the problems running Net-SNMP on -current
on i386 and amd64 (but for some unknown reason, not sparc64 for once).