FindCUDAToolkit: Understand NVHPC versioned math library layout
requested to merge robertmaynard/cmake:find_cudatoolkit_understand_nvhpc_math_library_location into master
The NVHPC packages bundle the CUDA math libraries in a sibling
directory (math_libs) instead of in with the rest of the
cuda libraries.
Depending on the NVHPC package the math_libs folder can have versioned subdirectories, therefore we prefer finding the same versions as the CUDA Toolkit and falling back to the latest when not possible.