Bug#1112291: libopenmpi40: tests fail: PMIx was unable to find a usable compression library

[Drew Parsons]

Source: openmpi
Followup-For: Bug #1112291

For the convenience of those reading the bug archives in the future,
the "previous" bug I was referring to was Bug#1112181
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1112181

These bugs follow the need to switch to openmpi's internal pmix library
due to issues with latest external pmix 6, see Bug#1111125
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1111125

Once the issue with external pmix is resolved, we'll want to reverse
these steps that we needed to take to activate the internal pmix.