On svn-auth-x509 branch, Deal with T61String/TeletexString encoding.

Actually, I'm just puting on this and doing what everyone else does
which is treat it as ISO-8859-1.  That's what Firefox, OpenLDAP and OpenSSL do.
From testing with my cert that contains and ISO-8859-1 encoded value in a
T61 labeled field, I can't find any major piece of software that doesn't
treat it as ISO-8859-1.  So when in Rome...

* subversion/libsvn_subr/x509parse.c
  (fuzzy_escape): Cleanup the comment.
  (x509name_to_utf8_string): Start treating T61String as ISO-8859-1 and
    expand some comments.

* subversion/tests/libsvn_subr/x509-test.c
  (cert_tests): Enable the T61 test and tweak the comments since the cert
    OpenSSL gave me isn't actually T.61 encoded but is ISO-8859-1.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1612775 13f79535-47bb-0310-9956-ffa450edef68