Add a complex benchmark

[jvoisin]

Some allocators are doing tradeoffs to perform very well on long-running complex workloads, so we should have some benchmarks to measure this. Maybe something like firefox running on a couple of webpages, or Apache?

Or maybe some lightweight javascript engine, running some javascript things. @TheShiftedBit suggested to compile nodejs or python to use the memory allocator, and run some workload on it.

[jvoisin]

Openfoam and relion sound like nice candidates.

Thanks to @nab-os for the suggestion!

[jvoisin]

Or maybe the compilation of oasis, or self-compiling cproc.

[jvoisin]

Or maybe some lightweight javascript engine, running some overkill javascript things.