This patch provides the first preparation step in getting ready to integrate the latest BBR and Rack from NF.
It adds:
- New tcp log values and options
- Adds a new concept that a stack can support that will always define the ending sequence in a connection. This can be useful for stacks that use it for BB logging purposes and put out the log on exit to provide a quick reference as to why a tcp stack exited. Of course at this point no one uses it so the code is just "available", though not used.