On svn-auth-x509 branch, deal with character encodings (mostly).

This still doesn't properly handle T61String/TeletexString, largely because
I don't quite have it done and the encoding is a mess.

* subversion/libsvn_subr/x509parse.c
  (fuzy_escape, x509name_to_utf8_string): New function.
  (x509parse_dn_gets): Remove terribly hacky "conversion" and use
    x509name_to_utf8_string() instead.

* subversion/tests/libsvn_subr/x509-test.c
  (cert_tests): Add certs with UTF-8, UniversalString, BMPString and T61String
    encoded strings.  The T61 cert is disabled for now.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1612757 13f79535-47bb-0310-9956-ffa450edef68