zebra: make rib_dump() compatible with IPv6 RIB

[DL: resolved conflicts in zebra_rib.c]
[DL: fix usage with --disable-ipv6]
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/zebra/rib.h b/zebra/rib.h
index 1c54879..97a20af 100644
--- a/zebra/rib.h
+++ b/zebra/rib.h
@@ -386,7 +386,7 @@
 extern int nexthop_has_fib_child(struct nexthop *);
 extern void rib_lookup_and_dump (struct prefix_ipv4 *);
 extern void rib_lookup_and_pushup (struct prefix_ipv4 *);
-extern void rib_dump (const char *, const struct prefix_ipv4 *, const struct rib *);
+extern void rib_dump (const char *, const struct prefix *, const struct rib *);
 extern int rib_lookup_ipv4_route (struct prefix_ipv4 *, union sockunion *);
 #define ZEBRA_RIB_LOOKUP_ERROR -1
 #define ZEBRA_RIB_FOUND_EXACT 0