This implementation uses GnuTLS function
gnutls_x509_crt_check_hostname(). It has a bit different rules regarding
matching (allows wildcards in some cases, but does not use suffix
matching) compared to the internal implementation used with OpenSSL.
However, these rules are sufficiently close to each other to be of
reasonable use for most cases.
Signed-off-by: Jouni Malinen <j@w1.fi>