Make sure that polykinded Typeable is defaultable (Trac #8931)
Make sure that polykinded Typeable is defaultable (Trac #8931)

(cherry picked from commit 791f4fa24dd6929ab2e55c9f8b870d8078337427)

hferreiro/replay,lukexi/ghc-7.8-arm64,hferreiro/replay,hferreiro/replay,lukexi/ghc-7.8-arm64,lukexi/ghc-7.8-arm64,hferreiro/replay,hferreiro/replay,lukexi/ghc-7.8-arm64,hferreiro/replay,hferreiro/replay,lukexi/ghc-7.8-arm64