Fixes#14263
If the new decoder code fails, it now falls back to the old legacy code
and tries that also.
Tested manually using gost engine master.
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/14266)