NVSHMEM in CUDA plugin

[Joel Berkeley]

Hi,

I'm seeing

libnvshmem_host.so.3: cannot open shared object file: No such file or directory

when I run my custom-build CUDA PJRT plugin. I installed NVSHMEM, but then I get 

nvshmem_transport_ibrc.so.3: cannot open shared object file: No such file or directory

I see some mention of MELLANOX IBRC or sth as an optional dependency for NVSHMEM, but the install looks complex, and I don't even support multi-GPU atm. I'm already using `--config nonccl` to avoid NCCL. Is there any way I can similarly avoid NVSHMEM for now?