Apitrace of "Manhattan 3.1" results in hangs across hardware backends when run through virgl

The benchmark Manhattan 3.1 gfxbench uses compute shaders that result in hangs on i965, Nvidia, and RadeonSI when run through virgl, but it runs fine directly on the host. A trace to reproduce the problem can be found here.

A first assessment of the problem seems to indicate that the barriers used in the compute shaders might misbehave.