lang/intel-compute-runtime: enable debug variables

$ clinfo | fgrep 'Platform Version'

Platform Version                                OpenCL 3.0

$ ForceOCLVersion=12 clinfo | fgrep 'Platform Version'

Platform Version                                OpenCL 1.2

https://github.com/intel/compute-runtime/blob/21.32.20609/shared/source/debug_settings/debug_variables_base.inl