Remove the last dependency on an APR private header.
Incidentally, also stop pretending that we support Windows 95.

* subversion/libsvn_subr/io.c: Do not include apr_arch_file_io.h.
   Remove conditionals based on the APR_HAS_UNICODE_FS symbol.
  (io_win_file_attrs_set): Remove Win95-specific code.
  (io_win_read_link): Likewise.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1534976 13f79535-47bb-0310-9956-ffa450edef68