radv: implement out-of-order rasterization when it's safe on VI+

radv: implement out-of-order rasterization when it's safe on VI+

Disabled by default for now, it can be enabled with
RADV_PERFTEST=outoforder.

No CTS regressions on Polaris, and all Vulkan games I tested
look good as well.

Expect small performance improvements for applications where
out-of-order rasterization can be enabled by the driver.

Loosely based on RadeonSI.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>