ospf6d: address more trivial compiler warnings

* ospf6_main.c: include required headers
* ospf6_asbr.h: idem
* ospf6_spf.c
  * ospf6_spf_install(): remove unused variables
diff --git a/ospf6d/ospf6_asbr.h b/ospf6d/ospf6_asbr.h
index 7166aa3..72644df 100644
--- a/ospf6d/ospf6_asbr.h
+++ b/ospf6d/ospf6_asbr.h
@@ -22,6 +22,13 @@
 #ifndef OSPF6_ASBR_H
 #define OSPF6_ASBR_H
 
+/* for struct ospf6_prefix */
+#include "ospf6_proto.h"
+/* for struct ospf6_lsa */
+#include "ospf6_lsa.h"
+/* for struct ospf6_route */
+#include "ospf6_route.h"
+
 /* Debug option */
 extern unsigned char conf_debug_ospf6_asbr;
 #define OSPF6_DEBUG_ASBR_ON() \
diff --git a/ospf6d/ospf6_main.c b/ospf6d/ospf6_main.c
index a7a96a1..ced2ef2 100644
--- a/ospf6d/ospf6_main.c
+++ b/ospf6d/ospf6_main.c
@@ -34,8 +34,13 @@
 #include "plist.h"
 #include "privs.h"
 #include "sigevent.h"
+#include "zclient.h"
 
 #include "ospf6d.h"
+#include "ospf6_top.h"
+#include "ospf6_message.h"
+#include "ospf6_asbr.h"
+#include "ospf6_lsa.h"
 
 /* Default configuration file name for ospf6d. */
 #define OSPF6_DEFAULT_CONFIG       "ospf6d.conf"
diff --git a/ospf6d/ospf6_spf.c b/ospf6d/ospf6_spf.c
index 04367f0..e78f7f6 100644
--- a/ospf6d/ospf6_spf.c
+++ b/ospf6d/ospf6_spf.c
@@ -282,8 +282,7 @@
 {
   struct ospf6_route *route;
   int i, j;
-  struct ospf6_vertex *prev, *w;
-  struct listnode *node, *nnode;
+  struct ospf6_vertex *prev;
 
   if (IS_OSPF6_DEBUG_SPF (PROCESS))
     zlog_debug ("SPF install %s hops %d cost %d",