[MLton] x86_64 port status + powerpc

[Matthew Fluet]

> On May 7, 2006, at 1:57 AM, Wesley W. Terpstra wrote:
>> I will take a look at ppc osx ...
>
> So far, I've needed the attached patch for the runtime.

Thanks.  The patch looks pretty good.

> After these minor fixes, I got the attached c-types.sml.

Interesting... Darwin has different signedness for some of the system 
types.  Looks like it makes sense to define a special signature for C 
integer types, which supports sufficient operations and conversions, 
without exposing the signedness.

Obviously, from below, we need things like {to,from}Large{Int,Word} to be 
in this signature.