Add getmtu and setmtu interface commands

Bug: 9372485

Change-Id: I0dfa6b1f973426d67f976a9c79be8de90e3d9c19
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
diff --git a/InterfaceController.h b/InterfaceController.h
index 5943a9a..b8bbc92 100644
--- a/InterfaceController.h
+++ b/InterfaceController.h
@@ -35,6 +35,8 @@
 	int interfaceCommand(int argc, char *argv[], char **rbuf);
 	int setEnableIPv6(const char *interface, const int on);
 	int setIPv6PrivacyExtensions(const char *interface, const int on);
+	int getMtu(const char *interface, int *mtu);
+	int setMtu(const char *interface, const char *mtu);
 
  private:
 	void *libh_;