Allow `State# s` argument/result types in `ccall` FFI imports
This ticket is to allowing code like
{-# LANGUAGE UnliftedFFITypes #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE UnboxedTuples #-}
module M where
import GHC.Exts
foreign import ccall unsafe "foo" c_foo :: Int# -> State# s -> State# s
foreign import ccall unsafe "bar" c_foo :: Int# -> State# s -> (# State# s, Int# #)See also discussion in #9281 (closed)