vendor-gems: fix output location, also run pristine.
vendor-gems: fix output location, also run pristine.

This means the output is consistent and ensures that we get rid of any local cruft when installing.

MikeMcQuaid/brew,claui/brew,konqui/brew,reitermarkus/brew,Homebrew/brew,mahori/brew,sjackman/homebrew,nandub/brew,mahori/brew,claui/brew,JCount/brew,claui/brew,JCount/brew,konqui/brew,sjackman/homebrew,Homebrew/brew,EricFromCanada/brew,EricFromCanada/brew,vitorgalvao/brew,Homebrew/brew,vitorgalvao/brew,reitermarkus/brew,konqui/brew,nandub/brew,JCount/brew,sjackman/homebrew,MikeMcQuaid/brew,MikeMcQuaid/brew,nandub/brew,sjackman/homebrew,mahori/brew,vitorgalvao/brew,reitermarkus/brew,Homebrew/brew,claui/brew,konqui/brew,MikeMcQuaid/brew,mahori/brew,vitorgalvao/brew,reitermarkus/brew,nandub/brew,EricFromCanada/brew,EricFromCanada/brew,JCount/brew