forum lib.php is badly written. It is huge and requires a lot of other library code.

(Probably a lot of code there should be moved to locallib.php.)

Anwyay, it is not a problem for us, since we don't use forum.php, so it is disappoining to see forum lib.php showing up in our profiling as 2% of the page-load time.

This simple patch seems to fix it, but it might cause regressions.