netd: Route MTU

- Route may include optional MTU parameter
- Change route is added so routes don't need to be deleted then re-added
- Add/Del/Change functions to pass route info as parcel

Bug: 142892223
Test: new unit tests
Change-Id: Idc32ecb0520b1f4136b3fe0e3f7b6800fb3005a6
diff --git a/server/PhysicalNetwork.cpp b/server/PhysicalNetwork.cpp
index 56f4ac3..2808fbe 100644
--- a/server/PhysicalNetwork.cpp
+++ b/server/PhysicalNetwork.cpp
@@ -88,8 +88,8 @@
         // If any of these operations fail, there's no point in logging because RouteController will
         // have already logged a message. There's also no point returning an error since there's
         // nothing we can do.
-        (void) RouteController::addRoute(interface.c_str(), dst, "throw",
-                                         RouteController::INTERFACE);
+        (void)RouteController::addRoute(interface.c_str(), dst, "throw", RouteController::INTERFACE,
+                                        0 /* mtu */);
         (void) RouteController::removeRoute(interface.c_str(), dst, "throw",
                                          RouteController::INTERFACE);
     }