Bug#1139536: hypre: FTBFS: HYPRE_utilities.h:20:10: fatal error: mpi.h: No such file or directory

[Drew Parsons]

Source: hypre
Followup-For: Bug #1139536

mpi.h comes from MPI (libopenmpi-dev), and hypre was previously
able to find it using the standard mpi configuration methods.

The problem is reproducible at
https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/hypre.html

I might have though that an openmpi update introduced a bug that
needs to be fixed, but it has no recent updates.

We'll have to dig a little to understand what's changed.