Flextype Core: Cache - code fixes according Scrutinizer Tests.

The class Doctrine\Common\Cache\XcacheCache has been deprecated.

flextype/Cache.php

@@ -123,8 +123,6 @@ class Cache
                 $driver_name = 'apcu';
             } elseif (extension_loaded('wincache')) {
                 $driver_name = 'wincache';
-            } elseif (extension_loaded('xcache')) {
-                $driver_name = 'xcache';
             } else {
                 $driver_name = 'file';
             }
@@ -147,11 +145,6 @@ class Cache
             case 'wincache':
                $driver = new DoctrineCache\WinCacheCache();
                 break;
-            // The XcacheCache driver uses functions that come with the xcache extension
-            // https://xcache.lighttpd.net
-            case 'xcache':
-               $driver = new DoctrineCache\XcacheCache();
-                break;
             // The MemcachedCache drivers stores the cache data in Memcached.
             case 'memcached':
                 $memcached = new \Memcached();

site/plugins/admin/classes/SettingsManager.php

@@ -88,7 +88,6 @@ class SettingsManager
                             'file' => 'File',
                             'apcu' => 'APCu',
                             'wincache' => 'WinCache',
-                            'xcache' => 'Xcache',
                             'memcached' => 'Memcached',
                             'redis' => 'Redis',
                             'sqlite3' => 'SQLite3',