MINOR: conn_stream: add a new CS_FL_REOS flag

This flag indicates that the mux layer has already detected an end of
stream which will become CS_FL_EOS during a recv() once the rx buffer
is empty.
diff --git a/include/types/connection.h b/include/types/connection.h
index 9a57fce..16a82bb 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -73,7 +73,8 @@
 
 	CS_FL_ERROR         = 0x00000100,  /* a fatal error was reported */
 	CS_FL_RCV_MORE      = 0x00000200,  /* more bytes to receive but not enough room */
-	CS_FL_EOS           = 0x00001000,  /* End of stream */
+	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 */
 };