On the svn-auth-x509 branch, make the X509 parser API public.

* subversion/include/svn_x509.h: New. Declares svn_x509_parse_cert().

* subversion/libsvn_subr/x509.h
  (svn_x509_parse_cert): Remove declaration moved to public API.
   Also remove declaration of x509parse_dn_gets.

* subversion/libsvn_subr/x509parse.c
  (x509parse_dn_gets): Make static and move up in the file.

* subversion/svn/auth-cmd.c: Include svn_x509.h instead of libsvn_subr/x509.h.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1605200 13f79535-47bb-0310-9956-ffa450edef68