linkage_checker: handle system libraries on Big Sur
linkage_checker: handle system libraries on Big Sur

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