- make heap dumping work again
- refactor some of the heap statistics to work in OOM scenarios
  (ie be able to not collect the ones that would require allocation to track)
- collect some hcls statistics as well
- print stats to stderr rather than stdout
  - I think this makes more sense since it is not really part of the program
    output; it also makes it more likely that "PYSTON_RUN_ARGS=s" will work