dns: name anonymous functions

Ref: https://github.com/nodejs/node/issues/8913
PR-URL: https://github.com/nodejs/node/pull/9052
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/dns.js

@@ -181,7 +181,7 @@ function onlookupservice(err, host, service) {
 
 
 // lookupService(address, port, callback)
-exports.lookupService = function(host, port, callback) {
+exports.lookupService = function lookupService(host, port, callback) {
   if (arguments.length !== 3)
     throw new Error('Invalid arguments');
 
@@ -257,7 +257,7 @@ exports.resolveSoa = resolveMap.SOA = resolver('querySoa');
 exports.reverse = resolver('getHostByAddr');
 
 
-exports.resolve = function(hostname, type_, callback_) {
+exports.resolve = function resolve(hostname, type_, callback_) {
   var resolver, callback;
   if (typeof type_ === 'string') {
     resolver = resolveMap[type_];
@@ -277,12 +277,12 @@ exports.resolve = function(hostname, type_, callback_) {
 };
 
 
-exports.getServers = function() {
+exports.getServers = function getServers() {
   return cares.getServers();
 };
 
 
-exports.setServers = function(servers) {
+exports.setServers = function setServers(servers) {
   // cache the original servers because in the event of an error setting the
   // servers cares won't have any servers available for resolution
   const orig = cares.getServers();