MDL-25290 cache: Cache API integration with core

lib/setup.php

@@ -138,6 +138,14 @@ if (!defined('PHPUNIT_TEST')) {
     define('PHPUNIT_TEST', false);
 }
 
+// When set to true MUC (Moodle caching) will not use any of the defined or default stores.
+// The Cache API will continue to function however this will force the use of the cache_store_dummy so all requests
+// will be interacting with a static property and will never go to the proper cache stores.
+// Useful if you need to avoid the stores for one reason or another.
+if (!defined('NO_CACHE_STORES')) {
+    define('NO_CACHE_STORES', false);
+}
+
 // Servers should define a default timezone in php.ini, but if they don't then make sure something is defined.
 // This is a quick hack.  Ideally we should ask the admin for a value.  See MDL-22625 for more on this.
 if (function_exists('date_default_timezone_set') and function_exists('date_default_timezone_get')) {
@@ -468,6 +476,7 @@ require_once($CFG->libdir .'/sessionlib.php');      // All session and cookie re
 require_once($CFG->libdir .'/editorlib.php');       // All text editor related functions and classes
 require_once($CFG->libdir .'/messagelib.php');      // Messagelib functions
 require_once($CFG->libdir .'/modinfolib.php');      // Cached information on course-module instances
+require_once($CFG->dirroot.'/cache/lib.php');       // Cache API
 
 // make sure PHP is not severly misconfigured
 setup_validate_php_configuration();