Invalid parse for GADTs with strictness annotations

[NeilMitchell2]

Given this file:

{-# LANGUAGE GADTs #-}
data Foo where Bar :: !Int -> Foo

GHC loads it fine, but HSE has a parse error:

$ ghci
GHCi, version 6.12.3: http://www.haskell.org/ghc/
Prelude> import Language.Haskell.Exts
Prelude Language.Haskell.Exts> parseFile "Temp.hs"
ParseFailed (SrcLoc {srcFilename = "Temp.hs", srcLine = 2, srcColumn = 23}) "Parse error: !"

For once, I ran into this when developing Hoogle, not HLint, although it would also show up there.

[nibro]

Duplicate of #199