bug #3175227 [auth] Reset user cache on login.

libraries/common.lib.php

@@ -2528,6 +2528,13 @@ function PMA_generate_slider_effect($id, $message)
     <?php
 }
 
+/**
+ * Clears cache content which needs to be refreshed on user change.
+ */
+function PMA_clearUserCache() {
+    PMA_cacheUnset('is_superuser', true);
+}
+
 /**
  * Verifies if something is cached in the session
  *