Requiring `cl-lib` is not enough to get the side-effect-free property on
functions like cl-fifth.  To see this, run emacs -Q and evaluate:

    (progn
      (require 'cl-lib)
      (describe-function 'cl-fifth)
      (function-get 'cl-fifth 'side-effect-free))

Note that the form returns nil, and that the "This function does not
change global state" text is not there in the *Help* buffer.

This can be fixed by adding this to the above recipe:

    (require 'cl-macs)

I have attached a patch that fixes this, and also gets the proper
(put 'cl-foo 'side-effect-free t) forms into cl-loaddefs.el.

If this looks okay, I think we could do the same for the
(side-effect-free error-free) case as well.