turn off smux port 199

To turn off SMUX when you don't have the options of recompiling from source
to disable SMUX support, you have to give it an invalid IP address to bind
to. This may be OS specific. On Linux, if I put this in my snmpd.conf:

smuxsocket 1.0.0.0

I get an error at startup, and lsof or netstat show that snmpd is no longer
listenting on port 199. If you get and error message about the smuxsocket
token not being recognized, then you're out of luck. You'll have to recompile
from source (or just use local firewall rules to block connections to port
199).