Issue #3404405: Undefined variable $extensions_to_check in nagios_check_requirements()

Closes #3404405

nagios.module

@@ -458,7 +458,8 @@ function nagios_check_requirements() {
 
   // Cycle through enabled modules for requirements checks.
   $req_controller = new RequirementsController($config);
-  $req_controller->collectRequirements($extensions_to_check, $project_update_status, $enabled_projects);
+  $req_controller->collectRequirements(_nagios_extensions_to_check($nagios_ignored_extensions),
+    $project_update_status, $enabled_projects);
 
   // Check the requirements as to the most severe status:
   [$severity, $desc] = $req_controller->findMostSevereProblem();