`Keg::Relocation`: allow `-I`, `-L`, `-isystem` prefixes
`Keg::Relocation`: allow `-I`, `-L`, `-isystem` prefixes

MikeMcQuaid/brew,Homebrew/brew,JCount/brew,nandub/brew,nandub/brew,nandub/brew,JCount/brew,JCount/brew,MikeMcQuaid/brew,JCount/brew,MikeMcQuaid/brew,nandub/brew,Homebrew/brew,Homebrew/brew,MikeMcQuaid/brew,Homebrew/brew