Use ap_walk_config to configure directives

Use ap_walk_config to configure directives

The only expected change in behavior here is that directives
configured from LDAP are expected to now behave much more like ones
configured statically, since they now use the same code.  In practice,
this should not work out to a significant difference, but some
directives do seem to have a lot of code that
mod_vhost_ldap_translate_name didn't contain.  (I haven't investigated
this in-depth.)

I also removed logic to deal with r->uri[0] != '\0' && r->uri[0] !=
'/'.  I believe this is not actually relevant anymore, as the tranlate
hook no longer deals with translating to filenames itself, but I could
be mistaken.