Original issue is here: jnr/jffi#138

jffi's builds are done on a recent version of Debian that has a recent glibc. Unfortunately glibc does not produce dynamic bindings that are compatible with older versions, so the jffi stub fails to load. I attempted to make jffi builds use an older debian in CI, but it did not appear to link against an older glibc.

This should be dealt with for JRuby 9.4.3 but I'm not sure how best to do it.