st/mesa: add ES sample-shading support

We require the full ARB_gpu_shader5 for now, but in the future some
other CAP could get exposed to indicate that only the multisample-related
behavior of ARB_gpu_shader5 is available.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Dave Airlie <airlied@redhat.com>
2 files changed