Add args -- a variadic version of arg.
Add args -- a variadic version of arg.

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