geoip: Allow ASNs as zeros when creating NetDefn
so that GeoipDb can be created from files including ASNs generated with tor/scripts/maint/geoip/geoip-db-tool.
Closes #961 (closed)
so that GeoipDb can be created from files including ASNs generated with tor/scripts/maint/geoip/geoip-db-tool.
Closes #961 (closed)