TCP complete end status work.

[rrs]

Summary

The ending of a connection can tell us a lot about what happened i.e. did
it fail to setup, did it timeout, was it a normal close. Often times this is
useful information to help analyze and debug issues. Rack has had
end status for some time but the base stack as not. Lets go a ahead
and add in the missing bits to populate the end status.

Test Plan

Just bring up a connection with BB logging on and validate that
the end status gets populated at the close of the connection. For
extra points you can try killing the connection (with packet drill)
and see the various types of closes.