Fixed inet_ntoa usage bug in module_dns
Fixed inet_ntoa usage bug in module_dns

Previously we were reusing the same const buffer for all IP addresses
in dns fieldsets. This was bad and I feel bad.

shakenetwork/zmap,zmap/zmap,zmap/zmap,shakenetwork/zmap,shakenetwork/zmap,willscott/zmap,willscott/zmap,zmap/zmap,shakenetwork/zmap,willscott/zmap,willscott/zmap,shakenetwork/zmap,willscott/zmap