RAJA must be used when CUDA is selected.

[nychiang]

spack formula hiop@develop+cuda failed due to this section requires RAJA (but it is within the section without using RAJA).

@cameronrutherford While I will work on updating the CMake file in hiop, we also need to update the spack formula, to activate RAJA when cuda is selected.

[cameronrutherford]

See spack/spack#42407 - one line change to add this logic :)

[cameronrutherford]

@nychiang consider adding a warning to CMake for those users that are configuring HiOp without Spack