[Hugs-bugs] re-export bug

[Ross Paterson]

Bug reported by Bulat Ziganshin: load of C fails incorrectly in

	module A (f) where
	class A a where f :: a

	module B (module A) where
	import A

	module C where
	import B (f)

Same if A is

	module A (f) where
	data R = R { f :: Int }