contrib/wix/defines.wxi

formatter: add general way to switch hex/short functions

This seems a bit awkward, but it can avoid duplicates in annotate, tags,
branches and bookmarks.

I guess fm.hexfunc can eventually be removed (or redesigned) when it gets
template backend.

<Include>

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

</Include>