message: ENH: enable CUB in spack autogenerated hostconfigs
  Update Axom's spack package to enable CUB in the auto-generated
  host-configs when CUDA is enabled.
diff: @@ -407,8 +407,10 @@ class Axom(Package):
  if on_blueos_p9:
  cfg.write(cmake_cache_entry("AXOM_CUDA_ARCH", "sm_70"))
  + cfg.write(cmake_cache_option("AXOM_USE_CUB",True))
  else:
  cfg.write(cmake_cache_entry("AXOM_CUDA_ARCH", "sm_60"))
  + cfg.write(cmake_cache_option("AXOM_USE_CUB",True))
  cfg.write(cmake_cache_entry("CMAKE_CUDA_FLAGS" ,"-restrict -arch ${AXOM_CUDA_ARCH} -std=c++11 --expt-extended-lambda -G"))
  