ospf6d: add overload support

OSPFv3: Support setting/clearing overload bit on router

It is sometimes necessary for a router to gracefully remove itself from
the SPF tree i.e. it cannot act as a transit router. It does this by
setting the overload bit in the router LSA. This patch adds support for
enabling/disabling the overload bit.

Signed-off-by: Dinesh G Dutt <ddutt at cumulusnetworks.com>
Reviewed-by: Pradosh Mohapatra <pmohapat at cumulusnetworks.com>
[DL: patch applied with fuzz]
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/ospf6d/ospf6_top.h b/ospf6d/ospf6_top.h
index 27eb18c..02eb915 100644
--- a/ospf6d/ospf6_top.h
+++ b/ospf6d/ospf6_top.h
@@ -76,6 +76,7 @@
 };
 
 #define OSPF6_DISABLED    0x01
+#define OSPF6_STUB_ROUTER 0x02
 
 /* global pointer for OSPF top data structure */
 extern struct ospf6 *ospf6;