Add std::unordered_* C++11 allocator support

[Jason Merrill]

On 04/23/2013 03:25 PM, François Dumont wrote:
>      I reproduced the issue once I touch the hashtable_c++0x.cc file. I
> guess it is expected that modifying headers don't necessarily force a
> rebuild on the dependent source files. In this case is there a make
> target to force a rebuild of libstdc++ without rebuilding the whole gcc ?

I tend to do rm -rf <target>/libstdc++-v3; make all-target-libstdc++-v3

Jason