bsnmpd: change default process name/prefix from "snmpd" to "bsnmpd"

This is being done to prevent collisions between other snmp daemons,
like snmpd from net-snmp.

Add logging infrastructure hooks (newsyslog, syslogd) to support the
commit.

MFC after: 1 month
Reviewed by: arch@ (no objection)
Sponsored by: Dell EMC Isilon