Identifying 32 vs 64 bit OS?

[Jeremy DeHaan via Digitalmars-d-learn]

On Monday, 11 August 2014 at 06:17:22 UTC, ketmar via 
Digitalmars-d-learn wrote:
> On Mon, 11 Aug 2014 05:18:59 +0000
> Jeremy DeHaan via Digitalmars-d-learn
> <digitalmars-d-learn at puremagic.com> wrote:
>
> why do you need that info? D types has well-defined sizes (i.e 
> uint is
> always 32 bits, and so on).

I came up with a better solution for what I actually needed, but 
I was toying with some things in a rdmd build script for 
different kinds of compilation.