radv/gfx10: implement VK_EXT_post_depth_coverage

I did implement this extension a while ago but it didn't work
on pre GFX10 for some reasons. Now all CTS pass.

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