tcp: horizontal scaling improvments

- do not scale syn-ack window
- fix the max number of outstanding syns in builtin client
- fix syn-sent ack validation to use modulo arithmetic
- improve retransmit timer handler
- fix output buffer allocator leakeage
- improved debugging

Change-Id: Iac3bc0eadf7d0b494a93e22d210a3153b61b3273
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tcp/tcp_error.def b/src/vnet/tcp/tcp_error.def
index a4e46d6..0892231 100644
--- a/src/vnet/tcp/tcp_error.def
+++ b/src/vnet/tcp/tcp_error.def
@@ -38,4 +38,5 @@
 tcp_error (RST_SENT, "Resets sent")
 tcp_error (INVALID_CONNECTION, "Invalid connection")
 tcp_error (NO_WND, "No window")
-tcp_error (CONNECTION_CLOSED, "Connection closed")
\ No newline at end of file
+tcp_error (CONNECTION_CLOSED, "Connection closed")
+tcp_error (CREATE_EXISTS, "Connection already exists")
\ No newline at end of file