[Bug c++/60976] Compilation with G++ 4.9.0 is 2-3 times slower than with 4.8.2

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60976

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Most of the libstdc++ changes are for C++11 allocator support, which is
required for conformance. Some changes I made in <bits/alloc_traits.h> might
have negatively affected compile time though.