search_config_query_node_access_alter() can use "NOT IN" condition now.

I notice on line 174 of search_config.module that there's reference to a core bug which was preventing the "NOT IN" query condition from working. While I was working on another issue with search_config_query_node_Access_alter(), I tried using the commented out code that uses the NOT IN condition, instead of the workaround code below it. It works fine, so it appears that the core bug which was necessitating the (somewhat nasty) workaround has been fixed, meaning the workaround can be removed.

I've attached a patch which does just that.