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/lib/Makefile.am b/lib/Makefile.am
index 44d95bb..bd21092 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -27,7 +27,7 @@
 	str.h stream.h table.h thread.h vector.h version.h vty.h zebra.h \
 	plist.h zclient.h sockopt.h smux.h md5.h if_rmap.h keychain.h \
 	privs.h sigevent.h pqueue.h jhash.h zassert.h memtypes.h \
-	workqueue.h route_types.h
+	workqueue.h route_types.h libospf.h
 
 EXTRA_DIST = \
 	regex.c regex-gnu.h \