Since the parameters changed in z8, the benchmark on speed.z.cash is showing misleading results due to variability. (The quartile and extrema bars will still show the variability with 50 runs, they just won't jump around as much between benchmark data points.)
This makes sure that retransmits by a whitelisted peer also actually
result in a retransmit.
Further, this changes the logic to never relay in case we would assign
a DoS score, as we expect to get DoS banned ourselves as a result.
The setAskFor duplicate elimination was too eager and removed entries
when we still had no getdata response, allowing the peer to keep
INVing and not responding.
mapAlreadyAskedFor does not keep track of which peer has a request queued for a
particular tx. As a result, a peer can blind a node to a tx indefinitely by
sending many invs for the same tx, and then never replying to getdatas for it.
Each inv received will be placed 2 minutes farther back in mapAlreadyAskedFor,
so a short message containing 10 invs would render that tx unavailable for 20
minutes.
This is fixed by disallowing a peer from having more than one entry for a
particular inv in mapAlreadyAskedFor at a time.
