zink: support stencil-export

Enable pipe capability of exporting stencil from shader when Vulkan
extension is available.

Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>

Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9244>
2 files changed