Fix the decoder start type handling
Fix the decoder start type handling

If an explicit decoder start type was provided then it wasn't being
handled correctly in all cases. Specifically if a PEM start type was
provided then the decoder would fail.

Reviewed-by: Shane Lontis <452ce16516ceed26291fe7de3f8b53540d83864e@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/13050)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl