Fix snmpd installation failure

Sergio Durigan Juniorrequested to merge
sergiodj/net-snmp:fix-chown-snmpconf into master

Ref.: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1012693

The file $SNMP_DIR/snmpd.conf (which resolves to /var/lib/snmp/snmpd.conf) doesn't exist when snmpd has just been installed. For this reason, we have to guard the chown command to make sure it won't error on us.

Merge request reports