Clean up Core\Cache file

- Remove unused use statement
- Use explicit types for Memcache object

src/Core/Cache.php

@@ -5,7 +5,6 @@
 namespace Friendica\Core;
 
 use Friendica\Core\Config;
-use Friendica\Core\PConfig;
 use Friendica\Database\DBM;
 use dba;
 
@@ -17,13 +16,13 @@ require_once 'include/dba.php';
 class Cache
 {
 	/**
-	 * @brief Check for memcache and open a connection if configured
+	 * @brief Check for Memcache and open a connection if configured
 	 *
-	 * @return object|boolean The memcache object - or "false" if not successful
+	 * @return Memcache|boolean The Memcache object - or "false" if not successful
 	 */
 	public static function memcache()
 	{
-		if (!function_exists('memcache_connect')) {
+		if (!class_exists('\Memcache', false)) {
 			return false;
 		}
 
@@ -34,7 +33,7 @@ class Cache
 		$memcache_host = Config::get('system', 'memcache_host', '127.0.0.1');
 		$memcache_port = Config::get('system', 'memcache_port', 11211);
 
-		$memcache = new \Memcache;
+		$memcache = new \Memcache();
 
 		if (!$memcache->connect($memcache_host, $memcache_port)) {
 			return false;