Adding rassq-delete-all to lisp/subr.el.

[Lute Kamstra]

lisp/subr.el currently defines assq-delete-all.  What about providing
rassq-delete-all as well?

Lute.


(defun rassq-delete-all (value alist)
  "Delete from ALIST all elements whose cdr is `eq' to VALUE.
Return the modified alist.
Elements of ALIST that are not conses are ignored."
  (let ((tail alist))
    (while tail
      (when (and (consp (car tail)) (eq (cadr tail) value))
        (setq alist (delq (car tail) alist)))
      (setq tail (cdr tail)))
    alist))