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/NetdHwService.cpp b/server/NetdHwService.cpp
index b209aca..15855da 100644
--- a/server/NetdHwService.cpp
+++ b/server/NetdHwService.cpp
@@ -108,7 +108,8 @@
     RETURN_IF_NOT_OEM_NETWORK(netId);
 
     return toHalStatus(gCtls->netCtrl.addRoute(netId, ifname.c_str(), destination.c_str(),
-                                               maybeNullString(nexthop), false, INVALID_UID));
+                                               maybeNullString(nexthop), false, INVALID_UID,
+                                               0 /* mtu */));
 }
 
 Return <StatusCode> NetdHwService::removeRouteFromOemNetwork(