Changes

gather-topology: fix the gather of NVIDIA GPU NUMA info in /proc

It gathered a single file instead of a full directory.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

linux: don't hide the NVIDIA GPU node on non-POWER platforms

And allow to force hide it with HWLOC_KEEP_NVIDIA_GPU_NUMA_NODES=0.

These nodes were hidden by default on POWER because people
could use interleaved memory allocations across sockets,
but they would also interleave across GPU memory.

On NVIDIA Grace Hopper, interleaved allocation isn't much
of an issue since there's a single CPU node (and 1 single GPU
node per GPU slice).

Thanks to Antoine Morvan for the report.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>