-dcore-lint breakage with HEAD

[Sigbjorn Finne]

The following input

{-# OPTIONS -fglasgow-exts -dcore-lint #-}
module Foo where
data F = forall i . Integral i => Lit i
showF (Lit i) = show (toInteger i)

makes a HEAD compiler complain. ghc-5.00.1
(and 5.00) stays silent.

--sigbjorn