bug#72344: [PATCH] Add a version of cl-once-only which handles lists of forms

[Thuna]

> What does this have to do with Common Lisp or its
> emulation?

It is not about emulating Common Lisp, but it makes sense to keep this
next to `cl-once-only' as it is a variation of it.

> We shouldn't have _any_ functions, vars, macros, ...
> whose names use the prefix `cl-' (and not `cl--').
> It's really unfortunate that we still do have some.

I assume you mean that the `cl-' prefix should only be for names which
exist in Common Lisp, and while I am sympathetic towards that opinion
`cl-once-only' and `cl-with-gensyms' are macros which are firmly(?)
embedded in cl-lib.  The only other place where they would make sense,
as far as I am aware, is subr or subr-x, but I am not particularly
interested in making and defending the argument that they should be
moved there.