contrib/wix/defines.wxi

context: no longer accept diff options as dictionnary

Since we already broke the API earlier in this stack, there are no point to
introducing a new deprecation warning.

<Include>

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

</Include>