Merge branch 'FACK-loss-recovery-remove'

Yuchung Cheng says:

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remove FACK loss recovery

This patch set removes the forward-acknowledgment (FACK)
packet-based loss and reordering detection. This simplifies TCP
loss recovery since the SACK scoreboard no longer needs to track
the number of pending packets under highest SACKed sequence. FACK
is subsumed by the time-based RACK loss detection which is more
robust under reordering and second order losses.
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Signed-off-by: David S. Miller <davem@davemloft.net>