CL: sync C++ headers with Khronos

https://github.com/KhronosGroup/OpenCL-CLHPP at commit
cf9fc1035e8298c7ce65ee33066a660fd9892ebb

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
50 jobs for !2767 with cl-update in 12 seconds (queued for 1 minute and 2 seconds)
merge request