RADV/RadeonSI Benchmarks On Mesa 18.0

With Mesa 18.0 now well into its feature freeze and this quarterly update to Mesa OpenGL/Vulkan drivers bringing many new features and improvements as covered in our Mesa 18.0 feature overview here are some benchmarks comparing the Mesa 18.0 RadeonSI/RADV driver performance to the current 17.3 stable series and the older 17.2 series as well.