WIP: cogl-winsys-glx: Add a heuristically calculated presentation_time (3.36 backport)
The Nvidia driver (on Xorg) lacks presentation timestamps. They're always zero. This means it can unpredictably fall into triple or quad-buffering resulting in high latency and irregular stutters (when the buffer queue fills up and blocks). This branch adds heuristically calculated presentation timestamps so that doesn't happen anymore.
WIP only because this is a backport waiting for the master version !1309 (closed) to land.