[dpdk-dev] v2 mempool: add stack (lifo) mempool handler

[David Hunt]

This patch set adds a fifo stack handler to the external mempool
manager.

This patch set depends on the 3 part external mempool handler
patch set (v5 of the series):
http://dpdk.org/ml/archives/dev/2016-May/039364.html

v2 changes:
  * updated based on mailing list feedback (Thanks Stephen)
  * checkpatch fixes.