bug#59786: Allowing arbitrary expressions in cl-labels

[Drew Adams]

> I'd like to hear what other people think,

FWIW, I think that our CL emulation library
should emulate CL.  (Shocking, I know.)  In this 
case, `cl-labels' should emulate CL's `labels'.

It's bad enough that we've added some non-CL
stuff to our CL library over the years (instead
of putting it elsewhere and not giving it prefix
`cl-').  It's worse when we co-opt a CL name to
do something other than emulate the CL thingie
that has that name.

It's fine for Emacs Lisp to add whatever we like,
including a `labels'-like function that acts
differently from CL `labels'.  What's misguided,
IMO, is for us to use the name `cl-labels' for
such non-`labels' behavior.  Add a new function
for that, without prefix `cl-'.

I'd even like to see us backtrack on the other,
divergences from CL emulation that use CL names 
(but with prefix `cl-').

Just one opinion.