trial fix to null pointer free

[Nathan Froyd]

On Wed, Apr 27, 2011 at 04:23:42PM -0700, Xinliang David Li wrote:
> This can happen when the module does not have function bodies.
>
> -   VEC_free (cgraph_node_ptr, heap, cgraph_node_map);
> -   cgraph_node_map = NULL;
> +  if (cgraph_node_map)
> +    VEC_free (cgraph_node_ptr, heap, cgraph_node_map);
> +  cgraph_node_map = NULL;

Why are you doing this?  This is exactly what VEC_free already does.

-Nathan