Broker bug: routing loops

I found a bug in the bro-part of broker in bro/src/ and
bro/src/Event.h. I came across this when integrating my multi-hop
capable broker into bro in a deep-cluster setup.

The bug causes routing loops in between two directly peered bros when
both have subscribed to exactly the same prefix.

The current broker-integration branch is also affected by this. This
remained unnoticed until now, because peered bros in a cluster-setup
always use distinct subscription prefixes.However, that might not be the
case with future (deep cluster) deployments anymore.

I created a new branch of the broker-integration branch
(topic/mfischer/broker-fix) that fixes this bug. I also added another
test for it: bro/testing/btest/broker/remote_same_prefix.bro.

If there are no objections, I (or Daniel?) will merge it into the
broker-integration branch.


Let's merge it into master first, master can then be merged into the
integration branch. It's better to keep things as separate as possible
(I realize that the integration already has quite a bit in there ...)


Ok, fine with that. I will integrate my bugfix into master the next days.