session/tcp: improve preallocated segment handling

- add preallocated segment flag
- don't remove pre-allocated segments except if application detaches
- when preallocating fifos in multiple segments, completely fill
  a segment before moving to the next
- detach server application from segment-managers when deleting app
- batch syn/syn-ack/fin (re)transmissions
- loosen up close-wait and time-wait times

Change-Id: I412f53ce601cc83b3acc26aeffd7fa2d52d73b03
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/session/application.c b/src/vnet/session/application.c
index d105119..2b789c5 100644
--- a/src/vnet/session/application.c
+++ b/src/vnet/session/application.c
@@ -111,6 +111,8 @@
   hash_foreach (handle, index, app->listeners_table,
   ({
     vec_add1 (handles, handle);
+    sm = segment_manager_get (index);
+    sm->app_index = SEGMENT_MANAGER_INVALID_APP_INDEX;
   }));
   /* *INDENT-ON* */