Fix SPIR-V validation

[akharche]

This PR only affects spirv validation (NUMBA_DPPY_SPIRV_VAL=1). It resolves the problem with not appropriate debug instruction name for offloading with ocl.
If we don't add --spirv-debug-info-version=ocl-100 flag to spirv generating, we get the following error:
error: line 9: Invalid extended instruction import 'SPIRV.debug'

Add OpenCL.DebugInfo.100 as flag to SPIRV generator according to specification: https://www.khronos.org/registry/spir-v/specs/unified1/OpenCL.DebugInfo.100.html

[PokhodenkoSA]

Consider to add the flag only in debug mode.

[diptorupd]

@akharche please add some comments/documentation about what the flag does and why it is needed. The link to the manual is good, but a summary needs to be provided in the PR. Very hard to make out the motivation for the PR from the link to the spec.

[akharche]

@akharche please add some comments/documentation about what the flag does and why it is needed. The link to the manual is good, but a summary needs to be provided in the PR. Very hard to make out the motivation for the PR from the link to the spec.

@diptorupd the PR description was updated

[PokhodenkoSA]

@akharche we have no user docs about NUMBA_DPPY_SPIRV_VAL. Could you add it please?
Also it would be better to enable validation in CI.

[akharche]

@PokhodenkoSA It's a good idea to add validation to CI, but firstly we need to fix it fully