Add ability to compile with BACNET_PROTOCOL_REVISION<17 (#862)

src/bacnet/datalink/dlenv.c

@@ -918,6 +918,8 @@ void dlenv_init(void)
         tsm_invokeID_set((uint8_t)strtol(pEnv, NULL, 0));
     }
 #endif
+#if (BACNET_PROTOCOL_REVISION >= 17)
     dlenv_network_port_init();
+#endif
     dlenv_register_as_foreign_device();
 }