contrib/wix/defines.wxi

bdiff: avoid pointer arithmetic on void*

MSVC 2008 complains:

  mercurial/cext/bdiff.c(106) : error C2036: 'void *' : unknown size
  mercurial/cext/bdiff.c(107) : error C2036: 'void *' : unknown size

Maybe it's a gcc extension?

https://stackoverflow.com/questions/37460579/error-c2036-void-unknown-size

<Include>

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

</Include>