asn1: raise NOT_ENOUGH_DATA on header EOF

asn1: raise NOT_ENOUGH_DATA on header EOF

If BIO_read returns 0 with no buffered data, raise ASN1_R_NOT_ENOUGH_DATA
so callers see a specific error instead of a generic -1.

Signed-off-by: Joshua Rogers <MegaManSec@users.noreply.github.com>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28883)