LANL venado cufft path

[rfhaque]

On the LANL venado system, cuda installation is provided by the NVIDIA HPC SDK. The cuda toolkit libraries are located at /opt/nvidia/hpc_sdk/Linux_aarch64/24.7/cuda, while the cuda math libraries are located separately at /opt/nvidia/hpc_sdk/Linux_aarch64/24.7/math_libs.
In spack, cuFFT is not defined as a separate package but is instead searched at the location of the cuda toolkit. However, on venado, since the cufft (and other math libraries) are not co-located with the cuda toolkit, any application (e.g. lammps) that depends on cuFFT fails to build as it cannot find the required include and lib files.