MINOR: connstream: have a new flag CS_FL_KILL_CONN to kill a connection

This is the equivalent of SI_FL_KILL_CONN but for the connstreams. It
will be set by the stream-interface during the various shutdown
operations.
diff --git a/include/types/connection.h b/include/types/connection.h
index 434318f..f11cfb5 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -88,6 +88,7 @@
 	CS_FL_EOS           = 0x00001000,  /* End of stream delivered to data layer */
 	CS_FL_REOS          = 0x00002000,  /* End of stream received (buffer not empty) */
 	CS_FL_WAIT_FOR_HS   = 0x00010000,  /* This stream is waiting for handhskae */
+	CS_FL_KILL_CONN     = 0x00020000,  /* must kill the connection when the CS closes */
 
 	/* following flags are supposed to be set by the mux and read/unset by
 	 * the stream-interface :