bug#56641: Deprecate `lsh`

[Mattias Engdegård]

19 juli 2022 kl. 16.44 skrev Stefan Kangas <stefankangas@gmail.com>:

> When would I want to use `lsh' over `ash'?

Never, of course, but we shouldn't remove `lsh` as long as it's needed for 
compatibility with old packages that make pre-bignum assumptions, which is the 
reason for its existence (and semantics) in the first place.

And that's fine -- `lsh` can be kept indefinitely. However, I just removed 
several calls to `lsh` from new code in Emacs so evidently we need to up our 
information efforts a notch.

Adding a few words to the doc string may suffice, but a byte-compiler warning 
would help.