[Debian-astro-maintainers] Bug#867273: purify FTBFS on arm64 due to long-running test

[Edmund Grimley Evans]

I think that test takes a long time because it is using long double,
which on arm64 has 128 bits and is implemented in software. Possible
things to do:

* Change the default type (however and wherever it is defined) from
"long double" to "double" on arm64, and perhaps other architectures.

* Get that particular test to use 64-bit floats.

* Get that test to generate some output as it runs so that it does not
seem to be inactive.