EVP demo for XOF digest using SHAKE256

This demo optionally accepts a single command line argument, allowing
the output length to be specified.

Fixes #14106.

Reviewed-b

EVP demo for XOF digest using SHAKE256

This demo optionally accepts a single command line argument, allowing
the output length to be specified.

Fixes #14106.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17803)

show more ...