[PATCH] radv: Initial implementation of VK_EXT_queue_global_priority

[Andres Rodriguez]

This patch series implements VK_EXT_queue_global_priority, a vulkan extension
that focuses on providing scheduling guarantees.

For further information on the use case refer to:
https://lists.freedesktop.org/archives/amd-gfx/2016-December/004068.html

For some perf data on this initial implementation:
https://lists.freedesktop.org/archives/amd-gfx/2016-December/004257.html

Test apps available at:
https://github.com/lostgoat/Vulkan

Related amdgpu and libdrm_amdgpu patches can be found on the amd-gfx mailing list.

Additionaly, results for vk-cts -n *semaphore* on an RX480:

Test run totals:
  Passed:        1821/4046 (45.0%)
  Failed:        0/4046 (0.0%)
  Not supported: 2225/4046 (55.0%)
  Warnings:      0/4046 (0.0%)