On svn-auth-x509 branch, Extend the win32_xlate code to support converting
from UTF-16 and UTF-32 Big Endian.

* subversion/libsvn_subr/win32_xlate.c
  (UTF16BE, UTF32BE): New constants.
  (get_page_id_from_name): Use new constants and clean up some formatting.
  (svn_subr__win32_xlate_to_stringbuf): Add new code to handle the half of the
    conversion from UTF-16/32 BE to UTF-8 that Windows can't do.  Also fix
    formatting that didn't match our style while I'm at it.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1613382 13f79535-47bb-0310-9956-ffa450edef68