Update ffmpeg to version 20171123-a60b242
Update ffmpeg to version 20171123-a60b242

nikolasd/scoop,Cyianor/scoop,berwyn/scoop,vidarkongsli/scoop,rasa/scoop,kodybrown/scoop,yunspace/scoop,reelsense/scoop,coonce/scoop,lukesampson/scoop