tcp: Fix tcp_drain_oncpu()

Marker inpcb should always be moved.
systat - Add -altq display, bug fixes

* Add systat -altq.  This displays altq packet statistics in a nice
  [ifname x altqname] matrix.  Packets, bytes, and drops are displayed.

  Previously the only way to do this was to use 'pfctl -s queue -vvv'
  which is formatted so horribly that picking information out of it
  at a glance is impossible.

  Example usage:  systat -altq 1

* Correct a bug in -ifstat that caused the statistics to not display
  when switching out and then back into the ifstat display.