Memory Leak in `printWasm.gr`

[peblair]

These functions all leak memory at the moment. We should do one of the following:

• Fix the memory leaks
• Document the memory leaks (possibly acceptable, as these are intended for internal debugging as far as I understand).

[ospencer]

I think we should refactor these to not use pervasives and move them into runtime/debug so it's clear they're for debugging (and can leak all the memory they'd like).

[ospencer]

Done with #1481