Improve method finding CUDA libraries about relion HOT 2 OPEN

To answer your questions:

1. It maybe possible to use CUDA and then set a variable to store the option and then unset CUDA. Have proposed change in branch and will test to check it still works.
2. If CMP0146 is enabled it still doesn't solve the finding of some of the CUDA libraries. Not sure it helps other than retire the CUDA package.
3. It seems it was deprecated in 3.10 but FindCUDAToolkit seems to have been made available in 3.17 e.g. https://cmake.org/cmake/help/latest/module/FindCUDAToolkit.html - maybe be possible to wrap logic around the newer bits to keep the older bits - will take a look if old behaviour should stay.
4. I have just added a possible fix for the OpenMP support - will have to test.

from relion.

Thank you very much for your contribution. Indeed this has been on our TODO list (#1016) for a long time but we were unable to do anything concrete, so your patch is very useful.

I have several questions:

1. Is it possible to somehow keep the CUDA variable? I understand this conflicts with the module so it is reasonable to change the internal variable name, but we don't want to change user-facing arguments unless it is absolutely necessary.

2. when using the HPC SDK from Nvidia the cmake CUDA package cannot find the dependencies due to the change in file structure

   Does FindCUDA fail even when CMP0146 is enabled? This is to understand the urgency of the problem.

3. which was introduced in cmake 3.17 (but actually needs cmake 3.26 to work properly with HPC SDK).

   I thought it was introduced in 3.10 (as stated in the above CMP0146 page). Dropping <= 3.9 is probably fine but requiring 3.17 or 3.26 might be too strict. Can we make it compatible with both versions by failing back to FindCUDA when CMake is old?

4. Did you make sure NVCC compiler flags (e.g. OpenMP) are properly passed? This is critically important; without it, mutex locks in parallelization are disabled and the resulting binary is broken (e.g. #1038).

from relion.