MFC r211464:

MFC r211464:

  If a TCP connection has been idle for one retransmit timeout or more
  it must reset its congestion window back to the initial window.

  RFC3390 has increased the initial window from 1 segment to up to
  4 segments.

  The initial window increase of RFC3390 wasn't reflected into the
  restart window which remained at its original defaults of 4 segments
  for local and 1 segment for all other connections.  Both values are
  controllable through sysctl net.inet.tcp.local_slowstart_flightsize
  and net.inet.tcp.slowstart_flightsize.

  The increase helps TCP's slow start algorithm to open up the congestion
  window much faster.

  Reviewed by:	lstewart
  MFC after:	1 week

git-svn-id: svn://svn.freebsd.org/base/stable/8@211870 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f