bug#30635: No compiler warning if code forgets to require cl-lib

[Glenn Morris <rgm@gnu.org>]

Package: emacs
Version: 26.0.91

There's no compiler warning if a library uses cl-lib without requiring it.
I assume this is because bytecomp.el requires cl-lib.
Perhaps bytecomp can track cl-lib specially to work around this.

(I was wondering how the problem shown in 6288c3d went unspotted.)

Example:

foo.el:
(defun foo ()
  (cl-member-if 'cl-evenp '(1 2 3)))

emacs -Q -batch -f batch-byte-compile foo.el
  -> silently succeeds

emacs -Q -l foo.elc
M-: (foo)
 -> void-function cl-member-if