reorder: allow random number as starting point

reorder: allow random number as starting point

We use sequence numbers from a generator which has potentially started
long before the receiver. Therefore, the first number will typically
be > 0. The rte_reorder code will not work in this case, since the
packet is seen as outside of the buffer.

The patch instead records the first sequence number inserted as the
starting point.

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: Johan Faltstrom <johan.faltstrom@netinsight.net>
Acked-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>