microsoft/clc: If local size isn't specified either in the shader or at runtime, set it to (1,1,1)

Otherwise we can end up in situations like having divide-by-zero. If the optimization is smart enough that we end up with a constant divide-by-zero, then the DXIL validator will fail to sign, which can trigger fatal errors with CLOn12.

We want to run an initial translation of all kernels during program build, but at that point we don't know the local size to be able to specify it through kernel specialization data.

Closes: https://github.com/microsoft/OpenCLOn12/issues/20 Closes: https://github.com/darktable-org/darktable/issues/8700