Enable DLNA multi socket binding for linux

If not, DLNA on multiple interfaces not works for linux, for
example ZerotierOne VPN.

Emby.Dlna/Main/DlnaEntryPoint.cs

@@ -169,7 +169,8 @@ namespace Emby.Dlna.Main
             {
                 if (_communicationsServer == null)
                 {
-                    var enableMultiSocketBinding = _environmentInfo.OperatingSystem == MediaBrowser.Model.System.OperatingSystem.Windows;
+                    var enableMultiSocketBinding = _environmentInfo.OperatingSystem == MediaBrowser.Model.System.OperatingSystem.Windows ||
+                                                   _environmentInfo.OperatingSystem == MediaBrowser.Model.System.OperatingSystem.Linux;
 
                     _communicationsServer = new SsdpCommunicationsServer(_config, _socketFactory, _networkManager, _logger, enableMultiSocketBinding)
                     {