brew doctor: update expat check
brew doctor: update expat check

Apaprently both expat.framework and libexpat.framework exist
and interfere with CMake.

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