Advertises cl_khr_subgroup_ballot but doesn't provide SPIR-V support

[pjaaskel]

OpGroupNonUniformBallot is missing in SPIR-V before 1.3. Intel's OpenCL driver specifically advertises the cl_khr_subgroup_ballotextension which should imply SPIR-V support: "If the OpenCL environment supports the extension cl_khr_subgroup_ballot, then the environment must accept SPIR-V modules that declare the following SPIR-V capabilities...". However, the driver only supports SPIR-V 1.2, thus making it not possible to use the extension via SPIR-V.

Interestingly, if I patch llvm-spirv to produce 1.2 version number to the SPIR-V while still using the OpGroupNonUniformBallot, it allows me to use it.

(moved from https://github.com/KhronosGroup/SPIRV-LLVM-Translator/issues/1736)