diff: add missing rtm_send to nd6

[Jan Klemkow]

Hi,

This diff adds a missing routing message to the neighbor discovery code.
The message informs the userland about new reachable IPv6 nodes on the
network.  The IPv6 network stack acts more like the IPv4 port by this
diff.  Now, the behavior is like arpcache() in netinet/if_ether.c on
line 653.

Bye,
Jan

Index: nd6_nbr.c
===================================================================
RCS file: /cvs/src/sys/netinet6/nd6_nbr.c,v
retrieving revision 1.116
diff -u -p -r1.116 nd6_nbr.c
--- nd6_nbr.c   16 May 2017 12:24:04 -0000      1.116
+++ nd6_nbr.c   7 Jun 2017 22:11:31 -0000
@@ -715,6 +715,8 @@ nd6_na_input(struct mbuf *m, int off, in
                if (is_solicited) {
                        ln->ln_state = ND6_LLINFO_REACHABLE;
                        ln->ln_byhint = 0;
+                       /* Notify userland that a new ND entry is reachable. */
+                       rtm_send(rt, RTM_RESOLVE, ifp->if_rdomain);
                        if (!ND6_LLINFO_PERMANENT(ln)) {
                                nd6_llinfo_settimer(ln,
                                    ND_IFINFO(ifp)->reachable);