Ensure calling BIO_recvmmsg() with a dgram pair reports errors

Ensure calling BIO_recvmmsg() with a dgram pair reports errors

When calling BIO-recvmmsg() and using a dgram pair we were failing to
raise an error in the case that a problem occurs. This means that the
reason behind a failure cannot be detected and all problems are treated
as fatal even if they may not be.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20030)