recent bug in Custom dependencies.

[Luc Teirlinck]

After this change:

      * cus-dep.el (custom-make-dependencies): Simplify.
      Better follow the commenting conventions.

certain items are missing from Custom groups.  For instance, the
fringe group no longer contains `fringe-mode' as it should.  After
reverting the above change (to version 1:33 of cus-dep.el), it does
contain `fringe-mode'.

Sincerely,

Luc.