Fix build failures in Ubuntu 21.10 (#22952)

* Fix compile on Ubuntu 21.10

* Add missing c++17 optional refs in ui
old-commit-hash: 61f9b3e653b08900e6a5011320f383efbe443c14

SConstruct

@@ -189,6 +189,7 @@ env = Environment(
     "-Wno-inconsistent-missing-override",
     "-Wno-c99-designator",
     "-Wno-reorder-init-list",
+    "-Wno-error=unused-but-set-variable",
   ] + cflags + ccflags,
 
   CPPPATH=cpppath + [

selfdrive/ui/navd/route_engine.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <optional>
+
 #include <QThread>
 #include <QGeoCoordinate>
 #include <QGeoManeuver>

selfdrive/ui/ui.h

@@ -3,6 +3,7 @@
 #include <map>
 #include <memory>
 #include <string>
+#include <optional>
 
 #include <QObject>
 #include <QTimer>