dht_test fails on some architectures with GSL 2

[boutil]

Hi,

With GSL 2.x, tests from dht_test.rb fail on some architectures because of precision issues (the last digit may be wrong)
On Debian, it corresponds to i386,arm64, powerpc, s390x, and a few others.

See https://buildd.debian.org/status/fetch.php?pkg=ruby-gsl&arch=i386&ver=1.16.0.6%2Bdfsg1-1&stamp=1456772622

[v0dro]

Is it still failing with the new release? Could you check?

[rbalint]

Passing now in 2.1.0.1, thanks!