[Bug libstdc++/46572] forward_list nodes are not packed

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46572

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2010-11-19 22:25:32 UTC ---
>zero space or time overhead

We have a zero time overhead here.  packed would increase the time overhead
here really.