Adjust side-effect-free declarations

Adjust side-effect-free declarations

* lisp/emacs-lisp/byte-opt.el (side-effect-and-error-free-fns):
Add `eql` here.
* lisp/emacs-lisp/cl-macs.el (eql, cl-subst, cl-sublis):
Don't set the `side-effect-free` property here.
`cl-subst` and `cl-sublis` are not side-effect-free.
* lisp/emacs-lisp/cl-extra.el (cl-revappend):
Declare side-effect-free.
* lisp/emacs-lisp/cl-lib.el (cl-copy-list):
Declare side-effect-free and error-free.