Fix P2TP VPNs by adding an exception for VPN user.

BUG: 27199751
Change-Id: I1144228febba0c4cce1333fb39ea186d2963ed10
diff --git a/server/NetworkController.cpp b/server/NetworkController.cpp
index 8b1f84e..3364577 100644
--- a/server/NetworkController.cpp
+++ b/server/NetworkController.cpp
@@ -135,7 +135,8 @@
 }
 
 NetworkController::NetworkController() :
-        mDelegateImpl(new NetworkController::DelegateImpl(this)), mDefaultNetId(NETID_UNSET) {
+        mDelegateImpl(new NetworkController::DelegateImpl(this)), mDefaultNetId(NETID_UNSET),
+        mProtectableUsers({AID_VPN}) {
     mNetworks[LOCAL_NET_ID] = new LocalNetwork(LOCAL_NET_ID);
     mNetworks[DUMMY_NET_ID] = new DummyNetwork(DUMMY_NET_ID);
 }