openssl: some small cleanups

[icing]

• rename Curl_oss_check_peer_cert() to Curl_ossl_check_peer_cert()
• leave altname match loop after the first success when the match was an ip address
• remove static subj_alt_hostcheck() since it did not really do much
• use length based infof() output of altname, even though it does seem always to be nul terminated