Implement fastArray cache for multisite

info.xml

@@ -13,8 +13,8 @@
     <author>CiviCRM LLC</author>
     <email>info@civicrm.org</email>
   </maintainer>
-  <releaseDate>2019-06-13</releaseDate>
-  <version>2.7.1</version>
+  <releaseDate>2019-07-11</releaseDate>
+  <version>2.7.2</version>
   <develStage>stable</develStage>
   <compatibility>
     <ver>5.15</ver>

multisite.php

@@ -68,6 +68,7 @@ function multisite_civicrm_container(\Symfony\Component\DependencyInjection\Cont
       [
         'name' => 'descendant groups for org',
         'type' => ['*memory*', 'SqlGroup', 'ArrayCache'],
+        'withArray' => 'fast',
       ],
     ]
   ))->setFactory('CRM_Utils_Cache::create');