Wrap ghc-stage2
Wrap ghc-stage2

Fix #96 (c.f. #57 for stage1)

sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,snowleopard/shaking-up-ghc,bgamari/shaking-up-ghc,sdiehl/ghc,sdiehl/ghc,quchen/shaking-up-ghc,izgzhen/hadrian,snowleopard/hadrian,sdiehl/ghc