* lisp/emacs-lisp/nadvice.el: Support adding a given function multiple times.

* lisp/emacs-lisp/nadvice.el: Support adding a given function multiple times.
(advice--member-p): If name is given, only compare the name.
(advice--remove-function): Don't stop at the first match.
(advice--normalize-place): New function.
(add-function, remove-function): Use it.
(advice--add-function): Pass the name, if any, to
advice--remove-function.