EVP_MD_size() updates

For SHAKE algorithms we now return 0 from EVP_MD_size().
So all the places that check for < 0 needed to change to <= 0
(Otherwise the behaviour will be to digest nothing in most cases).

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25285)