ac/nir/ngg: add gs culling

ac/nir/ngg: add gs culling

Port from radeonsi.

Cull primitive after GS thread and before final vertex/primitive
export. GS culling is like VS/TES culling which read out saved
vertex positions of a primitive from LDS then call the primitive
culling algorithm to check whether it's visiable or not, only
passed primitives will be exported.

Unlike the VS/TES culling that read vertex index of a primitive
from VGPRs as shader args, GS will set a primitive complete flag
for each last vertex of a primitive in LDS, so that vertex thread
know the previous 1/2/3 vertex can form a primitive and do primitive
culling.

Acked-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17651>