AMD Wattman and more work making inroads on Linux via Libdrm

Huge commit today targeting Linux 4.17. So glad they are finally make such progress. The OpenCL/HSA integration is coming along well. Soon, the headaches will be gone and makes it easier for Blender Devs to see an error in OpenCL AMD and never have to ask, ``which platform is this from?’’ so long as Windows and Linux are on the modern stack.