doctor: be more forgiving about GREP_OPTIONS
doctor: be more forgiving about GREP_OPTIONS

Currently, `brew doctor` complains about GREP_OPTIONS being set,
regardless of its value. The cmake formula, for which this check was
introduced, is more specific about what actually makes it fail.

GREP_OPTIONS='--color=auto' will not cause the build to fail, so don't
warn about this.

Signed-off-by: Adam Vandenberg <34c2b6407fd5a10249a15d699d40f9ed1782e98c@gmail.com>

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