Intel Vulkan Linux Driver Lands Cull & Clip Distance Support

After a number of commits landed in mainline Mesa Git in the early hours of this morning, cull and clip distance support has been enabled for the open-source Intel Vulkan "ANV" Linux driver.

After work on NIR and ANV, clip and cull distance support was enabled. Following that ANV driver work was also an i965 driver change to use the NIR-based clip/cull lowering for their OpenGL driver too to benefit from using the same code-path for both drivers.

This is now another feature scratched off the Intel Vulkan driver's TODO list. Missing features still to be tackled for the Intel Vulkan Linux driver are FP64, tessellation, image gather extend, storage image without format, pipeline statistic queries, sparse memory, and per-sample-dispatch / minSampleShading. There are also some conformance test suite failures still to investigate on Haswell hardware, more code sharing is possible with the OpenGL driver, and various performance optimizations. More details via the ANV TODO list.