title: Unknown option "--enable-x11grab" when installing ffmpeg on centos (6.8)
body: <p>I am trying to install ffmpeg on a centos (6.8) machine.
  Specifically I have done the following:</p>
  
  <pre><code>sudo yum install yasm-devel libtheora-devel libvorbis-devel libX11-devel cmake gtk2-devel
  
  git clone http://git.videolan.org/git/ffmpeg.git
  cd ffmpeg
  ./configure --enable-gpl --enable-nonfree --enable-libtheora --enable-libvorbis  --enable-libx264  --enable-postproc --enable-version3 --enable-x11grab --enable-pthreads --enable-shared --enable-pic
  </code></pre>
  
  <p>The last line gives:</p>
  
  <pre><code>Unknown option "--enable-x11grab".
  </code></pre>
  
  <p>I did not find refernce tho this issue on a centos machine online.</p>
  
  <p>How could this be resolved?</p>