examples/packet_ordering: new sample app

examples/packet_ordering: new sample app

This new app makes use of the librte_reorder library.

It requires at least 3 lcores for RX, Workers (1 or more) and TX threads.
Communication between RX-Workers and Workers-TX is done by using rings.
The flow of mbufs is the following:
 * RX thread gets mbufs from driver, set sequence number and enqueue
   them in ring.
 * Workers dequeue mbufs from ring, do some 'work' and enqueue mbufs in
   ring.
 * TX dequeue mbufs from ring, inserts them in reorder buffer, drains
   mbufs from reorder and sends them to the driver.

Signed-off-by: Reshma Pattan <reshma.pattan@intel.com>
Signed-off-by: Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Declan Doherty <declan.doherty@intel.com>
[Thomas: add in examples/Makefile]