ENV.rb: Configure Objective-C++ compiler
ENV.rb: Configure Objective-C++ compiler

Ensures the `OBJCXX` environment variable is correctly set. Also adds `OBJC`
and `OBJCXX` to `ENV.remove_cc_etc`.

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