Make netd listen for and notify RDNSS options.

Bug: 9180552
Change-Id: Id2485b35c2299cfc455dd2b3b725136e5eb2a7e4
diff --git a/NetlinkManager.cpp b/NetlinkManager.cpp
index d3cffd7..32578a1 100644
--- a/NetlinkManager.cpp
+++ b/NetlinkManager.cpp
@@ -104,7 +104,8 @@
     if ((mRouteHandler = setupSocket(&mRouteSock, NETLINK_ROUTE,
                                      RTMGRP_LINK |
                                      RTMGRP_IPV4_IFADDR |
-                                     RTMGRP_IPV6_IFADDR,
+                                     RTMGRP_IPV6_IFADDR |
+                                     (1 << (RTNLGRP_ND_USEROPT - 1)),
          NetlinkListener::NETLINK_FORMAT_BINARY)) == NULL) {
         return -1;
     }