Fixes an infinite recursion error where Metasploit would attempt to
resolve a nameserver specified as a hostname in /etc/resolv.conf while
initializing.
Values for the namserver key in the resolv.conf file must be IP
addresses per the man page while the Resolver class in theory allows
them to be added by hostname however an existing one must be defined by
which it will be resolved.
This notably prevents IPv6 addresses with a scope ID from being allowed
in Ruby versions < 3.1.
Spencer McIntyre
cf6d324832