Add Config.hs (autoconf and configure rules).
Add Config.hs (autoconf and configure rules).

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