[MERGE-REQUEST] `make-archive' and existing directories

Hi,

I have a one-line patch in my archive[0] allowing for `make-archive' to
work properly even if the target directory already exists.  For an
illustration of the problem and how this affects Savannah users, you can
look at [1].

  patch-22
      make-archive: Allow for the creation of an archive when directory
      is not empty.

While I understand that, by having `make-archive' fail when the target
directory already exists, `tla' places itself on the "safe side", I
believe it currently does more harm than good, especially wrt. to
Savannah.  And, in any case, running the same `make-archive' command
twice will fail even with this patch applied (fortunately).

Thanks,
Ludovic.

[0] http://www.laas.fr/~lcourtes/software/arch-2005/
    tla--devo--1.3

[1] http://savannah.gnu.org/support/?func=detailitem&item_id=105531