Ensure RubyThread interrupts are Cleared

[original-brownbear]

RubyThread checks for interrupts with this code:

private boolean anyInterrupted() {
        return Thread.interrupted() || (interruptFlag & ~interruptMask) != 0;
    }

if we simply clear the Java thread, a subsequent invocation of Ruby code may still throw because the interrupted state wasn't cleared quickly enough on the RubyThread's interruptFlag as well.

=> Clear it via Thread.handle_interrupt (I put it in the conditional to avoid setting up the block on every call needlessly when there aren't any interrupts)

[original-brownbear]

@andrewvc no huge rush here I guess: but urgh the API here changed in JRuby 9k it seems :( => is this important enough to back port to 5.6? (if yes we could just add some conditional Ruby syntax and an eval to set up the interrupt clearing method I guess :))

[andrewvc]

@original-brownbear given that we're seeing this bug in 5.x now, I think that yes, we should support 5.x. My preference is not to backport it, since 5.x uses the same version of the filter here, but to use a conditional to use the correct API based on the current JRuby version.

[andrewvc]

Closing in favor of #131