TCP/session improvements

- Added svm fifo flag for tracking fifo dequeue events (replaces event
  length). Updated all code to switch to the new scheme.
- More session debugging
- Fix peek index wrap
- Add a trivial socket test client
- Fast retransmit/cc fixes
- tx and rx SACK fixes and unit testing
- SRTT computation fix
- remove dupack/ack burst filters
- improve ack rx
- improved segment rx
- builtin client test code

Change-Id: Ic4eb2d5ca446eb2260ccd3ccbcdaa73c64e7f4e1
Signed-off-by: Florin Coras <fcoras@cisco.com>
Signed-off-by: Dave Barach <dbarach@cisco.com>