OCSP response validation should not consider statuses of irrelevant certificates

When an OCSP responder is queried, it may elect to disclose the statuses of more certificates than were initially requested. These certificates may or may not be revoked. If we attempt to validate an OCSP response, and observe one or more revoked statuses for unsolicited certificate we should ignore them if (and only if) they are irrelevant for the chain we are attempting to validate.

Otherwise, we may fail to validate a valid chain.