Bug#944192: python3-h5py: 'import h5py' produces Open MPI message to stderr

[Jameson Graef Rollins]

Upstream suggests that debian should *not* compile python3-h5py against
OpenMPI by default, and based on the current performance of the package
in 2.10.0-2 I agree with them:

https://github.com/h5py/h5py/issues/1433#issuecomment-552640391

It's really quite annoying to have this package printing messages to
stderr (not to mention the performance issues mentioned above and in
#944617).

This is a pretty critical package for a lot of scientific applications,
and these new performance and messy output issues are proving to be
quite problematic.

Thanks for the attention.

jamie.