be more lenient when parsing alternate names

The current parser for alternate names bails out when it sees a alternative name format it doesn't understand, even when it can parse others. This prevents tls from validating certificates against a domain that is not the main subject when such unsupported alternate names are present. 
My patch changes the parser to ignore any fields it doesn't understand. This is certainly a crude hack, but it at least allows me to connect to a server.