[Bug libstdc++/69565] Heap operations could surely be faster

[morwenn29 at hotmail dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69565

--- Comment #3 from Morwenn <morwenn29 at hotmail dot fr> ---
It was a modified version of the following benchmark for sorting algorithms:
https://github.com/Morwenn/cpp-sort/blob/master/benchmarks/bench.cpp

I benchmarked the library's heap_sort (which is basically a copy-paste of
libc++'s make_heap + sort_heap) against the standard library's std::make_heap +
std::sort_heap. I was using MinGW with GCC 5.3 at the time, so the standard
functions corresponded to those in libstdc++.