Fix some default_cc behavior
Fix some default_cc behavior

Fixes Homebrew/homebrew#10245.
Fixes Homebrew/homebrew#10248.

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