Returns host information for a given IP address.
The IP address can either be an IPv4 or IPv6 address. The function waits
for all necessary IO to resolve. Upon success, it
HostEnt value if a host for the given name was found or
For this initial version of the crate, the lookup is a
first and only if that does fail to yield a result, a DNS query for
PTR records. This initial version also does not yet fill
the aliases list of the returned