cmake looks for `CUDA::cufft` under `nvidia-compilers` instead of `NVHPC`

[rsdmse]

The issue was revealed when building GROMACS 2026.0 with NVHPC 26.1:

CMake Error in src/testutils/CMakeLists.txt:
  Imported target "CUDA::cufft" includes non-existent path

    "/sfs/gpfs/tardis/applications/202606/software/standard/core/nvidia-compilers/26.1/Linux_x86_64/26.1/math_libs/include"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.

I manually created a symlink to NVHPC's math_libs inside nvidia-compilers and the cmake error went away.

Also there are broken symlinks in REDIST/math_libs/13.1/targets/x86_64-linux/lib (and maybe other directories).

[boegel]

@lexming Can you take a look at this?