Run shake script via stack from shake-build folder.
Run shake script via stack from shake-build folder.

See #110. [skip ci]

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