bug#12259: Add delete-trailing-whitespace to list of safe eval forms

[Mathieu Boespflug]

> I've just installed the patch below in the emacs-24 branch.

Thanks Stefan. That should do the trick.

-- Mathieu

> === modified file 'lisp/files.el'
> --- lisp/files.el     2012-08-15 16:29:11 +0000
> +++ lisp/files.el     2012-08-23 12:15:31 +0000
> @@ -2837,7 +2837,8 @@
>    ;; This should be here at least as long as Emacs supports write-file-hooks.
>    '((add-hook 'write-file-hooks 'time-stamp)
>      (add-hook 'write-file-functions 'time-stamp)
> -    (add-hook 'before-save-hook 'time-stamp))
> +    (add-hook 'before-save-hook 'time-stamp nil t)
> +    (add-hook 'before-save-hook 'delete-trailing-whitespace nil t))
>    "Expressions that are considered safe in an `eval:' local variable.
>  Add expressions to this list if you want Emacs to evaluate them, when
>  they appear in an `eval' local variable specification, without first