filesize warning for non existent file

For failed upload there was an stat performed on line 1284 of swftools.module, causing an warning to be displayed. I made the following modifications to fix it.

    // Build an array of types that SWF Tools can react to
    $mime_types = _swftools_mime_types();

    // If file is one of the above types, based on the extension, return headers
    $filepath = file_create_path($file);
    $fileexists = file_exists($filepath);
    if (isset($mime_types[$extension]) && $fileexists) {
      return array(
        'Content-Type: '. $mime_types[$extension],
        'Content-Length: '. filesize($filepath),
      );
    }