anv/gen9: expose VK_EXT_post_depth_coverage

Note that the use of ICMS_INNER_CONSERVATIVE disagrees with the GL driver.
Perhaps it's more performant than ICMS_NORMAL and is otherwise permitted?
Not sure, so I left it as-is.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/intel/vulkan/anv_pipeline.c

@@ -155,6 +155,7 @@ anv_shader_compile_to_nir(struct anv_pipeline *pipeline,
          .subgroup_vote = true,
          .stencil_export = device->instance->physicalDevice.info.gen >= 9,
          .storage_8bit = device->instance->physicalDevice.info.gen >= 8,
+         .post_depth_coverage = device->instance->physicalDevice.info.gen >= 9,
       },
    };