When the ret parameter is NULL the generated prime
is in rnd variable and not in ret.
CLA: trivial
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com> Reviewed-by: Paul Dale <paul.dale@oracle.com> Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8076)