<li>LIBGL_NO_DRAWARRAYS - if set do not use DrawArrays GLX protocol (for debugging)
<li>LIBGL_SHOW_FPS - print framerate to stdout based on the number of glXSwapBuffers
calls per second.
+<li>LIBGL_DRI3_DISABLE - disable DRI3 if set (the value does not matter)
</ul>