Bug#890887: babl FTBFS on s390x: FAIL: float-to-8bit

[Jeremy Bicha]

Control: severity -1 important

I've ignored build tests failures for babl on s390x in 0.1.46-2 since
the test isn't reliable and failure would hold up the gegl/gimp
transition.

Humorously, it looks like the build tests did pass this time though!

https://buildd.debian.org/status/logs.php?pkg=babl&arch=s390x

Thanks,
Jeremy Bicha