reinstall: add build-from-source switch.
reinstall: add build-from-source switch.

Fixes #5431.

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