Change the netId to nethandle mapping.

Being able to update this handle is necessary to ensure that
system-only OTAs do not break vendor code that relies on
nethandles.

Bug: 63052780
Test: walleye builds, boots, networking works
Test: MultinetworkApiTest CTS tests passes
Change-Id: I049a4ad2610ca68b8f56377b63be7e5e8ce76039

core/java/android/net/Network.java

@@ -356,13 +356,13 @@ public class Network implements Parcelable {
         // Multiple Provisioning Domains API recommendations, as made by the
         // IETF mif working group.
         //
-        // The HANDLE_MAGIC value MUST be kept in sync with the corresponding
+        // The handleMagic value MUST be kept in sync with the corresponding
         // value in the native/android/net.c NDK implementation.
         if (netId == 0) {
             return 0L;  // make this zero condition obvious for debugging
         }
-        final long HANDLE_MAGIC = 0xfacade;
-        return (((long) netId) << 32) | HANDLE_MAGIC;
+        final long handleMagic = 0xcafed00dL;
+        return (((long) netId) << 32) | handleMagic;
     }
 
     // implement the Parcelable interface