ospf6d: Add the missing ospf6 running check in show cmds

SYMPTOM:

If some of the ospfv3 commands like 'show ipv6 ospf6 route' are executed
with ospf6d daemon running but before having any ospfv3 configuration, then
ospf6d crash is seen.

ISSUE:

There are a few show commands, which are (unlike others) not checking if
ospf6 instance is initialized already.

FIX:

Add the missing checks, by using OSPF6_CMD_CHECK_RUNNING() in the commands
where its needed and not yet used.

Signed-off-by: Vipin Kumar <vipin@cumulusnetworks.com>
Reviewed-by: Pradosh Mohapatra <pmohapat@cumulusnetworks.com>
             Dinesh Dutt <ddutt@cumulusnetworks.com>
diff --git a/ospf6d/ospf6_area.c b/ospf6d/ospf6_area.c
index 0967482..1861fe7 100644
--- a/ospf6d/ospf6_area.c
+++ b/ospf6d/ospf6_area.c
@@ -666,6 +666,8 @@
   struct ospf6_route *route;
   struct prefix prefix;
 
+  OSPF6_CMD_CHECK_RUNNING ();
+
   ospf6_linkstate_prefix (ospf6->router_id, htonl (0), &prefix);
 
   for (ALL_LIST_ELEMENTS_RO (ospf6->area_list, node, oa))
@@ -701,6 +703,8 @@
   struct ospf6_route *route;
   struct prefix prefix;
 
+  OSPF6_CMD_CHECK_RUNNING ();
+
   ospf6_linkstate_prefix (ospf6->router_id, htonl (0), &prefix);
 
   if (inet_pton (AF_INET, argv[0], &area_id) != 1)
@@ -747,6 +751,8 @@
   struct ospf6_route_table *spf_table;
   unsigned char tmp_debug_ospf6_spf = 0;
 
+  OSPF6_CMD_CHECK_RUNNING ();
+
   inet_pton (AF_INET, argv[0], &router_id);
   ospf6_linkstate_prefix (router_id, htonl (0), &prefix);