[NETFILTER]: TCP conntrack: improve dead connection detection

Don't count window updates as retransmissions.

Signed-off-by: George Hansper <georgeh@anstat.com.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 9fc0ee6..238bbb5 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -688,13 +688,15 @@
 			if (state->last_dir == dir
 			    && state->last_seq == seq
 			    && state->last_ack == ack
-			    && state->last_end == end)
+			    && state->last_end == end
+			    && state->last_win == win)
 				state->retrans++;
 			else {
 				state->last_dir = dir;
 				state->last_seq = seq;
 				state->last_ack = ack;
 				state->last_end = end;
+				state->last_win = win;
 				state->retrans = 0;
 			}
 		}