[Bug libstdc++/56627] class hash instead of struct hash

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56627

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-03-16 02:22:39 UTC ---
I'm happy to fix things in libstdc++ that are broken and cause real problems
for clang users, but this is correct C++ and causes a spurious warning. Not a
bug, not worth wasting time on.