lib: use emitWarning instead of printDeprecationMessage

The process.emitWarning() API should be used for printing
deprecation warning messages rather than directly using the
internal/util#printDeprecationMessage

PR-URL: #8166
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

lib/_linklist.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const msg = require('internal/util').printDeprecationMessage;
-
 module.exports = require('internal/linkedlist');
-msg('_linklist module is deprecated. Please use a userland alternative.');
+process.emitWarning(
+  '_linklist module is deprecated. Please use a userland alternative.',
+  'DeprecationWarning');

lib/internal/util.js

@@ -63,7 +63,10 @@ exports._deprecate = function(fn, msg) {
 
   var warned = false;
   function deprecated() {
-    warned = exports.printDeprecationMessage(msg, warned, deprecated);
+    if (!warned) {
+      warned = true;
+      process.emitWarning(msg, 'DeprecationWarning', deprecated);
+    }
     if (new.target) {
       return Reflect.construct(fn, arguments, new.target);
     }

lib/module.js

@@ -196,10 +196,14 @@ Module._findPath = function(request, paths, isMain) {
     if (filename) {
       // Warn once if '.' resolved outside the module dir
       if (request === '.' && i > 0) {
-        warned = internalUtil.printDeprecationMessage(
-          'warning: require(\'.\') resolved outside the package ' +
-          'directory. This functionality is deprecated and will be removed ' +
-          'soon.', warned);
+        if (!warned) {
+          warned = true;
+          process.emitWarning(
+            'warning: require(\'.\') resolved outside the package ' +
+            'directory. This functionality is deprecated and will be removed ' +
+            'soon.',
+            'DeprecationWarning');
+        }
       }
 
       Module._pathCache[cacheKey] = filename;

lib/sys.js

@@ -1,10 +1,9 @@
 'use strict';
 
-const util = require('internal/util');
-
 // the sys module was renamed to 'util'.
 // this shim remains to keep old programs working.
 // sys is deprecated and shouldn't be used
 
 module.exports = require('util');
-util.printDeprecationMessage('sys is deprecated. Use util instead.');
+process.emitWarning('sys is deprecated. Use util instead.',
+                    'DeprecationWarning');