[MLton] -stop tc -warn-match false bug

[Stephen Weeks]

> [fluet@localhost test]$ mlton -stop tc -warn-match false -verbose 1 z.sml
> MLton MLTONVERSION (built Sat Jan 31 19:12:20 2004 on localhost)
> MLton starting
>    Type Check SML starting
>    Type Check SML raised in 2.79 + 1.50 (35% GC)
> MLton raised in 2.79 + 1.50 (35% GC)
> T has no conTycon property

Yeah, the problem is that with -stop tc -warn-match false I left the
defunctorizer running, and that doesn't make sense, since the
elaborator doesn't even generate sensible code with those flags.  I've
checked in a fix.