Word32.word -> Int32.int

[Stephen Weeks]

> No, nothing that fancy.  I was thinking more of optimizations revolving
> around
> 	Time.fromSeconds (LargeInt.fromInt xxx)
> where Time.fromSeconds contains a conversion from IntInf.int to Int.int, and
> the composition IntInf.toInt o LargeInt.fromInt being optimized to the
> identity.

Unfortunately, it's not very easy beacause IntInf.fromInt and IntInf.toInt are
implemented in SML code in the basis library and not as primitives.  It's pretty
much impossible to get the composition without treating them as primitives.  At
least they are implemented without any calls to C library gmp routines, and only
use word primitives.  So, it's just a bit of code.