Bug#888911: giac test failures with mpfr 4.0.0 on several architectures

[Matthias Klose]

Package: src:giac
Version: 1.2.3.57+dfsg1-2
Severity: serious
Tags: sid buster

see https://buildd.debian.org/status/package.php?p=giac

failing tests at least on the release architectures amd64 and armhf.