I never really implemented this properly, because I wasn't aware of the
clusters when doing the original pipeline barrier implementation. It
turns out that the Vulkan stages we get as part of the barriers are
actually good for something, because it turns out that the pipeline
state is split into stages, so earlier stages can run ahead of later
stages and sometimes we need to wait when an earlier stage depends on
the result of a later stage. This happens most often whenever a shader
reads the result of a color/depth attachment write, because attachment
writes happen in a logically later stage. However this could also happen
for a FS -> VS dependency.

Part-of: <mesa/mesa!12475>