[MLton] problems building mlton

[Stephen Weeks]

> As for the cvs version I get this error:
> 
> Compile SML starting
>       pre codegen starting
>          parseAndElaborate starting
> ../lib/mlton/pervasive/pervasive.sml:36.26-36.32 Error: unbound structure
> Real32
>          parseAndElaborate raised in 0.04 + 0.00 (0% GC)
>       pre codegen raised in 0.05 + 0.00 (0% GC)
>    Compile SML raised in 0.05 + 0.00 (0% GC)

This was bug in update-basis that prevents bootstrapping from older
versions of MLton.  I have checked in a fix.