pedantic error: incongruent exception specifications in TR1 <functional>

[Paolo Carlini]

Hi,

> The fix is either to remove the empty exception specification from
> bits/functional_hash.h or to add it in all the right places to
> tr1_impl/functional_hash.h.  Attached patch does the latter.

But I don't think it's ok, because the specialization taking a string  
by value can throw.

Paolo