wolfssl: enable CN validation

wolfssl: enable CN validation

WolfSSL added a wolfSSL_X509_check_host function to perform CN
validation in v3.10.4, depending on the build-time configure options:
--enable-nginx enables it for all supported versions;
--enable-opensslextra, since v3.14.2.

If the function is unavailable, then SSL_get_verify_result will be
called, and 'valid_cert' will be true if that call suceeds and we
have a peer certificate, just as it happens with openssl. Only
'valid_cn' will not be set.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>