documenting math function edge case behavior

Slightly related to: https://github.com/KhronosGroup/OpenCL-CTS/issues/2641

Both the OpenCL C spec and the OpenCL SPIR-V environment spec describe required edge case behavior for certain math functions:

* https://registry.khronos.org/OpenCL/specs/3.0-unified/html/OpenCL_C.html#edge-case-behavior
* https://registry.khronos.org/OpenCL/specs/3.0-unified/html/OpenCL_Env.html#_edge_case_behavior

These sections also reference parts of the C99 spec for additional edge case behavior, specifically section F.9. This is a bit confusing, though: it means that the reader needs to refer to two documents vs. one, and for SPIR-V especially, the reader needs to refer to the C99 specification vs. a SPIR-V document.

Should we document the required edge case behaviors for all math functions in the OpenCL documents instead, breaking the dependency on the C99 specification? Or, is this too much redundancy, and we should keep the reference as-is?

Start by comparing the OpenCL C and OpenCL Env edge-case sections named in the issue with the referenced C99 specification section F.9. Determine whether the OpenCL documents should reproduce the required behavior or retain the existing references; done means documenting and resolving that choice consistently for all math functions.

Written by the indexing model from the issue text.