specification doesn't clarify -cl-denorms-are-zero for half precision floating points

`-cl-denorms-are-zero` can be used to flush denorms for single and double precision floating point operations, but neither the OpenCL API spec nor the OpenCL Extension spec for `cl_khr_fp16` state anything in this regard.

Review the OpenCL API specification and the OpenCL Extension specification for cl_khr_fp16, focusing on the documented behavior of -cl-denorms-are-zero. Done means the specifications explicitly clarify whether the option applies to half-precision floating-point operations.

Written by the indexing model from the issue text.