Recognize defstruct slot names in various eieio functions

* lisp/emacs-lisp/cl-preloaded.el (cl-struct-define): Set
each slot's name's 'slot-name' property so that
'eieio--known-slot-name-p' can recognize them.  (Bug#62959)

Copyright-paperwork-exempt: yes

lisp/emacs-lisp/cl-preloaded.el

@@ -176,6 +176,7 @@ supertypes from the most specific to least specific.")
                        (i 0)
                        (offset (if type 0 1)))
                    (dolist (slot slots)
+                     (put (car slot) 'slot-name t)
                      (let* ((props (cl--plist-to-alist (cddr slot)))
                             (typep (assq :type props))
                             (type (if (null typep) t