[openmp][lit] Add support to OpenMP lit.cfg for ROCR_VISIBLE_DEVICES env-var

add support for ROCR_VISIBLE_DEVICES similar to name and purpose
as CUDA_VISIBLE_DEVICES

Differential Revision: https://reviews.llvm.org/D112503

GitOrigin-RevId: be03ef3ed1d18b8d5cf34816369dda94f474ccad
1 file changed