dev-cmd/bottle: add HOMEBREW_BOTTLE_SUDO_PURGE.
dev-cmd/bottle: add HOMEBREW_BOTTLE_SUDO_PURGE.

Add environment variable to optionally run `sudo purge` a few times to
potentially work around #6539.

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