Pass IPv6 through pppx(4)

[Denis Fondras]

Simple diff to allow IPv6 through pppx(4).

Denis

Index: net/if_pppx.c
===================================================================
RCS file: /cvs/src/sys/net/if_pppx.c,v
retrieving revision 1.66
diff -u -p -r1.66 if_pppx.c
--- net/if_pppx.c       11 Jul 2018 21:18:23 -0000      1.66
+++ net/if_pppx.c       4 Mar 2019 16:33:50 -0000
@@ -1047,6 +1047,11 @@ pppx_if_output(struct ifnet *ifp, struct
 #endif
        if (pipex_enable) {
                switch (dst->sa_family) {
+#ifdef INET6
+               case AF_INET6:
+                       proto = PPP_IPV6;
+                       break;
+#endif
                case AF_INET:
                        proto = PPP_IP;
                        break;