Fix for problem in fringe-mode

[Luc Teirlinck <teirllm@dms.auburn.edu>]

I finally found the solution to a problem I reported in early October.
At that time, I thought it was a bug in `partial-completion-mode', but
it is not.  It is a (trivial to fix) documentation bug in fringe-mode.

Problem:

Do M-x fringe-mode RET

Result:

Select fringe mode for all frames (SPACE for list):

For one of the possible four combinations of values of
`partial-completion-mode' and `completion-auto-help' SPACE will indeed
give you that list, for the other three it will do something else
(depending on which of the three combinations).  But `?' gives the
list in all cases.  So I propose to simply replace SPACE by ? in the
prompt, without any other changes.  In other words, if people are used
to use SPACE, it will still work.  If this is OK, I could commit it
once Savannah works again.

===File ~/fringe-diff=======================================
*** fringe.el.~1.8.~	Tue Oct 14 07:17:36 2003
--- fringe.el	Sat Dec 20 14:36:19 2003
***************
*** 119,125 ****
  Otherwise the negation of the fringe value in the currently selected
  frame parameter is used."
    (let ((mode (intern (completing-read
! 		       "Select fringe mode for all frames (SPACE for list): "
  		       '(("none") ("default") ("left-only")
  			 ("right-only") ("half") ("minimal"))
  		       nil t))))
--- 119,125 ----
  Otherwise the negation of the fringe value in the currently selected
  frame parameter is used."
    (let ((mode (intern (completing-read
! 		       "Select fringe mode for all frames (type ? for list): "
  		       '(("none") ("default") ("left-only")
  			 ("right-only") ("half") ("minimal"))
  		       nil t))))
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