MPI Variants: Linux

[ax3l]

Build three variants:

• nompi (default)
• openmpi
• mpich

Note the following:

• MPI for Windows (MSMPI) is not yet packaged with conda-forge, therefore MPI-support is Unix-only
• MPI runtime tests seam to fail / be misconfigured on OSX; MPI variants for OSX will be enabled in a follow-up PR

Allows users to install the following:

• conda install openpmd-api default, nompi variant
• conda install openpmd-api=*=mpi* any mpi-compatible implementation
• conda install openpmd-api=*=mpi_mpich* pick mpich variant. Same result as conda install mpich openpmd-api=*=mpi* .
• conda install openpmd-api=1.13=nompi* explicitly forbid MPI. Usually not necessary, as the build number offset causes nompi to be preferred unless MPI is explicitly requested.

Checklist

• [x] Used a fork of the feedstock to propose changes
• [x] Bumped the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• [x] Re-rendered with the latest conda-smithy (Use the phrase code>@<space/conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• [ ] Ensured the license file is being packaged.

[ax3l]

@minrk sorry to ping you on this: can you spot what's off with the mpiexec based tests on OSX? The ranks do not seam to know each other after mpiexec startup. Linux seams to work well with the settings I took from the hdf5 and mpi4py feedstocks.

[ax3l]

@conda-forge-admin, please rerender

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.