Revision 1501251

Implement reading symbolic links on Windows Vista or later. This fix 
issues with working copies located in symlinked folders.

* subversion/libsvn_subr/io.c
  (GETFINALPATHNAMEBYHANDLE): New.
  (win_dynamic_imports_state, get_final_path_name_by_handle_proc): New.
  (svn_io_read_link): Call io_win_read_link on Windows.
  (io_unicode_to_utf8_path): New. Copied from the APR function 
   unicode_to_utf8_path.
  (win_init_dynamic_imports): New.
  (io_win_read_link): Implement using GetFinaPathNameByHandleW() Windows API
   function.