Using api_get_configuration_value() to read config from file, instead of using global variable directly.

main/document/add_link.php

@@ -15,8 +15,7 @@ require_once '../inc/global.inc.php';
 require_once '../inc/lib/document.lib.php';
 require_once '../inc/lib/urlUtils.lib.php';
 
-global $_configuration;
-$fileLinkEnabled = $_configuration['enable_add_file_link'];
+$fileLinkEnabled = api_get_configuration_value('enable_add_file_link');
 
 if (!$fileLinkEnabled) {
     api_not_allowed(true);

main/document/document.php

@@ -1813,8 +1813,7 @@ if ($isAllowedToEdit ||
     }
 
     // "Add cloud link" icon
-    global $_configuration;
-    $fileLinkEnabled = $_configuration['enable_add_file_link'];
+    $fileLinkEnabled = api_get_configuration_value('enable_add_file_link');
     if ($fileLinkEnabled) {
         $actionsLeft .= Display::url(
             Display::return_icon('clouddoc_new.png', get_lang('AddCloudLink'), '', ICON_SIZE_MEDIUM),