dgram: add getters/setters for private APIs

This commit makes all previously private APIs available via
getters, setters, and wrapper functions.

PR-URL: #21923
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Wyatt Preul <wpreul@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/dgram.js

@@ -684,7 +684,69 @@ Socket.prototype.getSendBufferSize = function() {
 };
 
 
+// Legacy private APIs to be deprecated in the future.
+Object.defineProperty(Socket.prototype, '_handle', {
+  get() {
+    return this[kStateSymbol].handle;
+  },
+  set(val) {
+    this[kStateSymbol].handle = val;
+  }
+});
+
+
+Object.defineProperty(Socket.prototype, '_receiving', {
+  get() {
+    return this[kStateSymbol].receiving;
+  },
+  set(val) {
+    this[kStateSymbol].receiving = val;
+  }
+});
+
+
+Object.defineProperty(Socket.prototype, '_bindState', {
+  get() {
+    return this[kStateSymbol].bindState;
+  },
+  set(val) {
+    this[kStateSymbol].bindState = val;
+  }
+});
+
+
+Object.defineProperty(Socket.prototype, '_queue', {
+  get() {
+    return this[kStateSymbol].queue;
+  },
+  set(val) {
+    this[kStateSymbol].queue = val;
+  }
+});
+
+
+Object.defineProperty(Socket.prototype, '_reuseAddr', {
+  get() {
+    return this[kStateSymbol].reuseAddr;
+  },
+  set(val) {
+    this[kStateSymbol].reuseAddr = val;
+  }
+});
+
+
+Socket.prototype._healthCheck = function() {
+  healthCheck(this);
+};
+
+
+Socket.prototype._stopReceiving = function() {
+  stopReceiving(this);
+};
+
+
 module.exports = {
+  _createSocketHandle,
   createSocket,
   Socket
 };