vtn/opencl: add rint-support

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Tested-by: Marge Bot <mesa/mesa!4318>
Part-of: <mesa/mesa!4318>
54 jobs for !4318 with vtn-fixes in 58 minutes and 58 seconds (queued for 7 seconds)
merge request