simple.el: fix just-one-space breaking change

[Tim Van Holder]

The change to just-one-space of January 15th was a breaking one.
It introduces a non-optional parameter, breaking all current
invocations (which do not specify a parameter), such as
cc-electric-brace.
The trivial patch below fixes this by making the new parameter optional.

Note that given the function's name, it may be better to make a
`just-n-spaces' defun, and let just-one-space call that -
"(just-one-space 17)" is not as clear as "(just-n-spaces 17)".

Index: simple.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/simple.el,v
retrieving revision 1.681
diff -u -u -p -d -r1.681 simple.el
--- simple.el   15 Jan 2005 18:08:46 -0000      1.681
+++ simple.el   17 Jan 2005 08:30:01 -0000
@@ -647,13 +647,13 @@ If BACKWARD-ONLY is non-nil, only delete
        (skip-chars-backward " \t")
        (constrain-to-field nil orig-pos)))))
 
-(defun just-one-space (n)
+(defun just-one-space (&optional n)
   "Delete all spaces and tabs around point, leaving one space (or N spaces)."
   (interactive "*p")
   (let ((orig-pos (point)))
     (skip-chars-backward " \t")
     (constrain-to-field nil orig-pos)
-    (dotimes (i n)
+    (dotimes (i (or n 1))
       (if (= (following-char) ?\ )
          (forward-char 1)
        (insert ?\ )))