apache-httpd/2.4: Add modules for NixOS service.

The NixOS service module loads those modules by default. So we need to build
them here as well.

I'm not really sure why these modules are included by default, because (except
from maybe CGI) they obviously are only usable in very rare cases. Am I wrong?

Signed-off-by: aszlig <aszlig@redmoonstudios.org>