Update to use public Net::DNS API

Otherwize user get Net::DNS::....=HASH(0x1a7d060) garbage in place of
resolved hostnames. For example

$ printf  "127.0.0.1\n192.168.34.34\n" | jdresolve  --nostats -
Net::DNS::DomainName1035=HASH(0x21e0920)
192.168.34.34

jdresolve

@@ -857,7 +857,12 @@ sub checkresponse {
 				# For each DNS answer, check the data received
 				if ($type eq 'H') {
 					if (defined $_->{ptrdname}) {
+						if ($_->isa('Net::DNS::RR::PTR')) { 
+							# Fix for a new version of Net::DNS 
+							$hosts{$query}{NAME} = $_->rdatastr();
+						} else {
 						$hosts{$query}{NAME} = $_->{ptrdname};
+						}
 						$hosts{$query}{RESOLVED} = 'N';
 
 						$resolved = 1;