Unfortunately the existing test relied on packet payload in order to
map incoming packets to sockets.  In order to get this to work with TCP,
TCP_FASTOPEN needed to be used.

Since the fast open path is slightly different than the standard TCP path,
I created a second test which sends to reuseport group members based
on receiving cpu core id.  This will probably serve as a better
real-world example use as well.
Signed-off-by: NCraig Gallek <kraig@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>