ra_serf: Do not compare the CommonName of a certificate if there are
subjectAltName extensions of the DNS type when validating the certificate
as per RFC 2818.

* subversion/libsvn_ra_serf/util.c
  (ssl_server_certificate): add a boolean to know if there were san
    entries, skip the CN match if there were and move the failure
    flag outside of the CN match code.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1565531 13f79535-47bb-0310-9956-ffa450edef68