prebuilt openmpi4 + cpp bindings for AMD mi300x instances. to use:
```
wget -qO openmpi4.tar.gz https://huggingface.co/datasets/electroglyph/openmpi4/resolve/main/openmpi4-prebuilt.tar.gz
sudo tar -xzvf openmpi4.tar.gz -C /
sudo sh -c 'echo "/opt/openmpi/lib" > /etc/ld.so.conf.d/openmpi.conf'
sudo ldconfig
export PATH="/opt/openmpi/bin:$PATH"
export LD_LIBRARY_PATH="/opt/openmpi/lib:$LD_LIBRARY_PATH"
mpirun --version
```