android: Fix signature of get_nexthop()

src/frontends/android/app/src/main/jni/libandroidbridge/kernel/android_net.c

@@ -191,7 +191,8 @@ METHOD(kernel_net_t, get_source_addr_old, host_t*,
 }
 
 METHOD(kernel_net_t, get_nexthop, host_t*,
-	private_android_net_t *this, host_t *dest, int prefix, host_t *src)
+	private_android_net_t *this, host_t *dest, int prefix, host_t *src,
+	char **iface)
 {
 	return NULL;
 }