contrib/wix/defines.wxi

check-seclevel: pass a ui to the extension loader

Without this, if an import error occurs (as with pypy), the attempt to
report it fails since ui is None.

<Include>

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

</Include>