Update jruby dependency to create a workable build for OpenBSD

jruby 1.7.17 includes several fixes which are needed in order to run
on OpenBSD with 64-bit time_t (OpenBSD 5.5 and later).

There is still the issue of LOGSTASH-665 that's also affecting OpenBSD, but manually patching the files as suggested by Aldian works around it.