stats: check if stats vector entry is empty

When a stats entry is removed it is marked empty.
The stats client did not check for that and returned an empty string.
This resulted in blank lines in vpp_get_stats. Fix by returning null instead
and checking value.

Type: fix
Signed-off-by: Ole Troan <ot@cisco.com>
Change-Id: I08a39ba3ef4421bf275747a6300f97fe36791b50
diff --git a/src/vpp-api/client/stat_client.c b/src/vpp-api/client/stat_client.c
index 01ed7c7..1c31ea0 100644
--- a/src/vpp-api/client/stat_client.c
+++ b/src/vpp-api/client/stat_client.c
@@ -512,6 +512,11 @@
     return 0;
   vec = get_stat_vector_r (sm);
   ep = vec_elt_at_index (vec, index);
+  if (ep->type == STAT_DIR_TYPE_EMPTY)
+    {
+      stat_segment_access_end (&sa, sm);
+      return 0;
+    }
   if (!stat_segment_access_end (&sa, sm))
     return 0;
   return strdup (ep->name);