Support response files regardless of which GHC `hsc2hs` was compiled with

See also https://ghc.haskell.org/trac/ghc/ticket/15758

The hsc2hs-0.68.4 release was already revised with a lower bound `base >= 4.12` to
mitigate the issue solver-side
(http://hackage.haskell.org/package/hsc2hs-0.68.4/revisions/)

This improves upon #9