[WIP] Profile GC

[PalumboN]

Here is the work related to GC profiling (used for the IWST paper).

How to use it?

1. Build the VM
2. Run any program using the generated VM (as normal)
3. A file called scavenge.log (but it has info about the FullGCs also) will be generated in the current directory
4. You can plot some charts from that log file using https://github.com/tesonep/benchy/pull/23

WIP

Still need some work to be integrated. I also want to be sure that performance is not affected (significantly) if the profiler is off.