Merge pull request #12225 from adomokos/no_need_for_active_support_concern

Removing ActiveSupport::Concern, it's not needed

actionpack/lib/action_controller/metal/head.rb

 module ActionController
   module Head
-    extend ActiveSupport::Concern
-
     # Return a response that has no content (merely headers). The options
     # argument is interpreted to be a hash of header names and values.
     # This allows you to easily return a response that consists only of