Fix the subr-arity returned by native compiled functions with lots of args

Fix the subr-arity returned by native compiled functions with lots of args

This fixes bug #58739.  Make subr-arity return, e.g., (12 . 12) rather than
(12 . many) for a function with a fixed number of arguments more than 8.

* lisp/emacs-lisp/comp.el (comp-prepare-args-for-top-level): Only return a cdr
of 'many when there are &rest arguments.

* src/eval.c (eval_sub): Also check for a fixed number of args over 8 when
using the nargs + *args calling convention.
(funcall_subr): Also check numargs <= 8 before using the fixed args calling
convention.  Include the case numargs > 8 in the aMany calling convention.

* src/lisp.h (DEFUN): Amend the comment about MANY.