Inform dnsmasq of the downstream ifaces.

This lets it filter the dns requests so we're not a public dns forwarder/spambot.

bug:7530468
Change-Id: I102fad738aff717e6ac40d4ac5a8d39a6fe2d2ca
diff --git a/TetherController.h b/TetherController.h
index d3106eb..02cd412 100644
--- a/TetherController.h
+++ b/TetherController.h
@@ -52,6 +52,9 @@
     int tetherInterface(const char *interface);
     int untetherInterface(const char *interface);
     InterfaceCollection *getTetheredInterfaceList();
+
+private:
+    int applyDnsInterfaces();
 };
 
 #endif