network - Fix multiple MP races

network - Fix multiple MP races

* Fix sonewconn() races.  sonewconn() was attaching prior to changing
  the socket->so_port, relying on the caller to set the socket->so_port.
  This resulted in a race where userland wound up with visibility on the
  socket and could issue commands, like close(), which would end up going
  to the original protocol thread instead of the post-connect protocol thread
  which was handling the sonewconn().

  Thus the close() could message the backend to detach and compete
  against the sonewconn() because the detach message was going to
  a different protocol thread.

* When the socket->so_port is changed the inpcb was not being moved
  from the old pcbinfo->pcblisthead list to the new one, resulting
  in MP races later on during removal.

* Add more debugging kprintf()s.

* Clean up sosetport() use, remove the now-unused *_soport_attach().

Reported-by: Many