[TCP]: Make invariant check complain about invalid sacked_out

Earlier resolution for NewReno's sacked_out should now keep
it small enough for this to become invariant-like check.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed