Improve fifo allocator performance

Improve fifo allocator performance

- add option to preallocate fifos in a segment
- track active fifos with doubly linked list instead of vector
- update udp redirect test code to read fifo pointers from API call
  instead of digging them up from fifo segment header
- input-node based active-open session generator

Change-Id: I804b81e99d95f8690d17e12660c6645995e28a9a
Signed-off-by: Dave Barach <dave@barachs.net>
Signed-off-by: Florin Coras <fcoras@cisco.com>
Signed-off-by: Dave Barach <dbarach@cisco.com>