xf86-video-modesetting TearFree Gets Fixed Up For A/V De-Synchronization Issue

A few months back the generic xf86-video-modesetting X.Org driver added TearFree page-flipping support. The option eliminates screen tearing without the use of a compositor and was seen as a win by many for this generic DDX driver that works atop the modern DRM/KMS kernel drivers. But a rather annoying issue was discovered that could lead to audio/video synchronization problems was uncovered and is now fixed in the latest driver code...