Superenv: determine_optflags should return a string
Superenv: determine_optflags should return a string

This is saved in HOMEBREW_OPTFLAGS and later mutated by
ENV.universal_binary, so if this returns nil the sub will fail.

pseudocody/brew,jmsundar/brew,MikeMcQuaid/brew,AnastasiaSulyagina/brew,JCount/brew,staticfloat/brew,vitorgalvao/brew,rwhogg/brew,rwhogg/brew,claui/brew,claui/brew,DomT4/brew,EricFromCanada/brew,AnastasiaSulyagina/brew,JCount/brew,gregory-nisbet/brew,Linuxbrew/brew,zmwangx/brew,mgrimes/brew,pseudocody/brew,hanxue/linuxbrew,muellermartin/dist,vitorgalvao/brew,reelsense/brew,maxim-belkin/brew,nandub/brew,reitermarkus/brew,Homebrew/brew,nandub/brew,bfontaine/brew,DomT4/brew,tonyg/homebrew,reitermarkus/brew,jmsundar/brew,konqui/brew,ilovezfs/brew,gordonmcshane/homebrew,JCount/brew,sjackman/homebrew,mahori/brew,maxim-belkin/brew,jmsundar/brew,maxim-belkin/brew,bfontaine/brew,palxex/brew,EricFromCanada/brew,JCount/brew,amar-laksh/brew_sudo,konqui/brew,reitermarkus/brew,alyssais/brew,AnastasiaSulyagina/brew,MikeMcQuaid/brew,toonetown/homebrew,muellermartin/dist,gregory-nisbet/brew,mahori/brew,Linuxbrew/brew,reitermarkus/brew,palxex/brew,Linuxbrew/brew,gregory-nisbet/brew,DomT4/brew,aw1621107/brew,vitorgalvao/brew,sjackman/homebrew,mahori/brew,DomT4/brew,reelsense/brew,mgrimes/brew,alyssais/brew,hanxue/linuxbrew,aw1621107/brew,amar-laksh/brew_sudo,staticfloat/brew,zmwangx/brew,konqui/brew,gordonmcshane/homebrew,vitorgalvao/brew,tonyg/homebrew,gordonmcshane/homebrew,bfontaine/brew,Homebrew/brew,MikeMcQuaid/brew,mahori/brew,Homebrew/brew,sjackman/homebrew,tonyg/homebrew,amar-laksh/brew_sudo,hanxue/linuxbrew,nandub/brew,mistydemeo/homebrew,palxex/brew,Linuxbrew/brew,Homebrew/brew,sjackman/homebrew,reelsense/brew,muellermartin/dist,aw1621107/brew,claui/brew,EricFromCanada/brew,claui/brew,rwhogg/brew,nandub/brew,ilovezfs/brew,MikeMcQuaid/brew,zmwangx/brew,ilovezfs/brew,EricFromCanada/brew,alyssais/brew,mgrimes/brew,toonetown/homebrew,staticfloat/brew,mistydemeo/homebrew,mistydemeo/homebrew,pseudocody/brew,toonetown/homebrew,konqui/brew