merge r3201, r3204, r3411:

merge r3201, r3204, r3411:

ngx_http_autoindex_module fixes:

*) reset cached dirent.d_type after stat()
   this fixes slash after link to a directory in ngx_http_autoindex_module;
*) use cached dirent.d_type as hint on all systems

   the issues has been introduced in r2235

*) fix ngx_utf8_cpystrn(): it did not fully copy utf-8 string