Severity: wishlist

The old `cl.el' library was marked obsolete in Emacs 27.1.  We now get
two warnings if we try to require it, for example:

foo.el:3:1: Warning: Package cl is deprecated
foo.el:3:1: Warning: cl package required at runtime

I don't think there is any need to maintain the specific warnings about
the `cl' package.  The regular deprecation warnings should be
sufficient: they discourage use of cl.el altogether.

The attached patch removes all specific warnings about cl.  It also
updates the documentation to be even more discouraging regarding use of
cl.el and the even older cl-compat.el.

Finally, I noticed that the help screen for functions and variables from
cl.el do not actually say explicitly that they are obsolete.  The patch
marks most function and variable aliases in cl.el as obsolete.  This is
minor, but I believe somewhat helpful.

Thoughts?