mesa/st: implement hardware accelerated GL_SELECT

mesa/st: implement hardware accelerated GL_SELECT

Use an internal geometry shader to handle input primitives. Do full
accurate culling and clipping in the shader and output hit result and
min/max depth to a SSBO for final being written to select buffer.

With multiple result slots in SSBO we can left multiple draws on the
fly and wait them done when buffer is full or exit GL_SELECT mode.

This provides quicker selection response compared to software based
solution. Tested on Discovery Studio 2020: some complex model needs
1~2s selection response time originally, now it's almost selected
immidiately.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15765>