ospf6d/ospfd: refactor some common defines

Rearranging common defs and structures for use betweeen OSPFv2 and
OSPFv3.  Created a new file called libospf.h under lib directory to
hold defines that are common between OSPFv2 and OSPFv3 code bases.

[DL: split of defines refactor from timer refactor]
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/ospf6d/ospf6d.h b/ospf6d/ospf6d.h
index 2ac6300..13699d6 100644
--- a/ospf6d/ospf6d.h
+++ b/ospf6d/ospf6d.h
@@ -24,6 +24,9 @@
 
 #define OSPF6_DAEMON_VERSION    "0.9.7r"
 
+#include "libospf.h"
+#include "thread.h"
+
 /* global variables */
 extern struct thread_master *master;