Bug#1023788: getfem: fails to build from source on s390x

[Drew Parsons]

severity 1023788 important
thanks

The problem is hidden in 5.4.2+dfsg1-2 by simply skipping tests on 
s390x.

This will enable getfem 5.4 to migrate to testing, so downgrading 
severity. But leaving the bug open since the problematic behaviour still 
needs to be fixed.

Drew