* lisp/loadup.el (oclosure): Load before `nadvice`

* lisp/loadup.el (oclosure): Load before `nadvice`

* lisp/loadup.el (oclosure): Load before `nadvice`.

* lisp/emacs-lisp/cl-generic.el (cl--generic-class-parents): Move to
`cl-preloaded.el`.
(cl--generic-struct-specializers, cl-generic--oclosure-specializers)
(cl--generic-specializers-apply-to-type-p): Use its new name.

* lisp/emacs-lisp/cl-preloaded.el (cl--class-allparents): New function
moved from `cl-generic.el`.

* lisp/emacs-lisp/oclosure.el (oclosure-define): Use it.

* lisp/emacs-lisp/cl-macs.el (pcase--mutually-exclusive-p):
Don't advise if `nadvice` has not yet been loaded.