[v3] fix libstdc++/52476

[Paolo Carlini]

Hi,
> Attached patch applied.
>
> 2012-03-16  François Dumont <fdumont@gcc.gnu.org>
>
>         PR libstdc++/52476
>         * include/bits/hashtable.h (_Hashtable<>::_M_rehash_aux): Add.
>         (_Hashtable<>::_M_rehash): Use the latter.
>         * testsuite/23_containers/unordered_multimap/insert/52476.cc: 
> New.
>         * testsuite/23_containers/unordered_multiset/insert/52476.cc: 
> New.
Francois, at your ease, I think it's time to apply the fix to 4_7-branch 
too and resolve the PR. By the way, Daniel confirmed in private email 
that mainline works just fine now.

Thanks,
Paolo.