Bug#895748: mpi-default-dev: add riscv64 to list of MPI arches

[Drew Parsons]

Package: mpi-default-dev
Version: 1.10
Severity: normal

Both openmpi and mpich now build on the new arch riscv64.
So riscv64 should be added to the list of default arches.

Whether default to openmpi or to mpich, your choice.
We've been defaulting to openmpi for most arches, but that's mainly
because historically mpich supported a smaller set of arches than Debian
supports.

Now that mpich builds on all arches, it could be a good opportunity to 
review and discuss whether we want to keep openmpi as the default
default, or whether we want to switch to mpich.

Again historically, openmpi had more bugs than mpich, mainly because it
was trying to do more things (support more arches, for instance).

We seem to have convergence at this point in time.  OpenMPI has now 
fixed the old egregious bugs, while mpich now supports many arches.

So you could say it doesn't really matter which one we one we choose,
except perhaps for particular specific HPC configurations, where one
implementation may have advantage over the other.  But Debian can't
optimise for that, unless a survey can get back to us on which one
better suits our actual HPC clients.

Maybe we could swap the default MPI from release to release, to keep 
them both lively.

Drew

-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.15.0-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE=en_AU.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages mpi-default-dev depends on:
ii  libopenmpi-dev  2.1.1-8

mpi-default-dev recommends no packages.

mpi-default-dev suggests no packages.

-- no debconf information