Add the apcu caching ability for performance (#7276)

* add the apcu caching ability for performance
When the PHP extension APCu is loaded, the settings class and the auto_loader will cache their results across requests in RAM. For more information about the APCu extension visit the PHP page: https://www.php.net/apcu

* use global instead of default terminology

resources/classes/cache.php

@@ -187,6 +187,17 @@ class cache {
 				closelog();
 			}
 
+		//check for apcu extension
+			if (function_exists('apcu_enabled') && apcu_enabled()) {
+				//flush everything
+				apcu_clear_cache();
+			}
+
+		//remove the autoloader file cache
+			if (file_exists(sys_get_temp_dir() . '/' . auto_loader::FILE)) {
+				@unlink(sys_get_temp_dir() . '/' . auto_loader::FILE);
+			}
+
 		//cache method memcache
 			if ($this->method === "memcache") {
 				// connect to event socket