VPN: close the socket in protectVpn() to avoid leaking descriptors.

Change-Id: Idda0c2ea1770abc490566e894711bcb08f60b354
diff --git a/core/java/android/net/IConnectivityManager.aidl b/core/java/android/net/IConnectivityManager.aidl
index d6f5643..d95fc8d 100644
--- a/core/java/android/net/IConnectivityManager.aidl
+++ b/core/java/android/net/IConnectivityManager.aidl
@@ -100,7 +100,7 @@
 
     void setDataDependency(int networkType, boolean met);
 
-    void protectVpn(in ParcelFileDescriptor socket);
+    boolean protectVpn(in ParcelFileDescriptor socket);
 
     boolean prepareVpn(String oldPackage, String newPackage);