vppinfra: use stored vec header size to find header

Type: refactor
Change-Id: Iaa1e43c87c5725ab33ea8489bff2a7bda18b9c79
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vlib/node.c b/src/vlib/node.c
index 41b9ee7..2c408d6 100644
--- a/src/vlib/node.c
+++ b/src/vlib/node.c
@@ -364,7 +364,7 @@
   vec_add1 (nm->nodes, n);
 
   /* Name is always a vector so it can be formatted with %v. */
-  if (clib_mem_is_heap_object (vec_header (r->name, 0)))
+  if (clib_mem_is_heap_object (vec_header (r->name)))
     n->name = vec_dup ((u8 *) r->name);
   else
     n->name = format (0, "%s", r->name);