bug#15234: 24.3.50; Make C-x u repeatable

[Jambunathan K]

Drew Adams <drew.adams@oracle.com> writes:

>> Make C-x u repeatable. 
>
> FWIW, this is what I use:
>
> (defun undo-repeat (arg)
>   "Same as `undo', but repeatable even on a prefix key.
> E.g., if bound to `C-x u' then you can use `C-x u u u...' to repeat."
>   (interactive "*P")
>   (undo arg)
>   (set-temporary-overlay-map (let ((map  (make-sparse-keymap)))
>                                (define-key map "u" 'undo-repeat)
>                                map)))
>
> (global-set-key [remap undo] 'undo-repeat)

I want it right within stock Emacs.  Not in my .emacs, not in a package
floating in wikis.