[Bug libstdc++/57840] ::std ::result_of is undocumented

[fdumont at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57840

--- Comment #2 from François Dumont <fdumont at gcc dot gnu.org> ---
Created attachment 30596
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30596&action=edit
The modified hashtable implementation

To replace hashtable.h in include/bits