contrib/wix/defines.wxi

py3: update tests/test-check-py3-compat.t

The lower part of the test runs with python 3 and hence remain unchanged.

<Include>

  <?if $(var.Platform) = "x64" ?>
    <?define IsX64 = yes ?>
  <?else?>
    <?define IsX64 = no ?>
  <?endif?>

</Include>