fix dir separator in test

Author: weltling

ext/bz2/tests/bug72447.phpt

@@ -12,4 +12,4 @@ stream_filter_append($fp, 'bzip2.compress', STREAM_FILTER_WRITE, $param);
 fclose($fp);
 ?>
 --EXPECTF--
-Warning: stream_filter_append(): Invalid parameter given for number of blocks to allocate. (0) in %s/bug72447.php on line %d
+Warning: stream_filter_append(): Invalid parameter given for number of blocks to allocate. (0) in %s%ebug72447.php on line %d