apache-httpd: Add unixd for 2.4, needed by "User".

Beginning with 2.4 mod_unixd is needed to supply Unix usernames and groups for
the web server. For details please have a look at:

http://httpd.apache.org/docs/2.4/upgrading.html#commonproblems



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