[MLton] problems building mlton

[Stephen Weeks]

> I was happily running a fixpoint on both machines and both returned the
> following after finishing the first compilation round of the compiler:
> 
> Creating constants file.
> /home/lziarek/mlton/build/bin/mlton -build-constants true >tmp.c
> /home/lziarek/mlton/build/bin/mlton -output tmp tmp.c
> tmp.c:1: parse error before "off"

Whoops.  I accidentally left on a debugging message.  Sorry about
that.  It's now fixed.