Recent changes assumed OpenCL 2.0 platform. This adds a check to see if we are compiling on an OpenCL 2.0 platform. Patch was tested on: * AMD Radeon Pro WX 7100 with amdgpu-pro-19.50-1011208-ubuntu-18.04 drivers * AMD Vega 64 with amdgpu-pro-20.10-1048554-ubuntu-18.04 drivers * AMD RX 5700 with amdgpu-pro-20.10-1048554-ubuntu-18.04 drivers Reviewed By: Brecht van Lommel Differential Revision: https://developer.blender.org/D7637