Question about mi_collect

In MoarVM, whenever we do what we call a "full" garbage collection run, we call `malloc_trim()` if it's available. I thought it would make sense to now also call `mi_collect(true)`. However, while testing this out I noticed some odd interaction with heaptrack and our `--full-cleanup` runtime option (which frees everything upon exit, instead of just letting the OS clean up). I use the `--full-cleanup` option when I'm profiling with heaptrack, so it gives an accurate account of leaks (i.e., we try for no leaks with `--full-cleanup`). Using a heaptrack that I've added support for mimalloc to, everything looks good normally. However, when I added the `mi_collect(true)` call, now even with `--full-cleanup` heaptrack reports massive leaks. Is there something I should add to my patch to heaptrack to get it to properly handle `mi_collect`?

Start by reproducing the interaction between mi_collect(true), malloc_trim(), heaptrack, and MoarVM's --full-cleanup option. Compare heaptrack's results with and without mi_collect(true), then determine whether the heaptrack mimalloc support needs adjustment so full cleanup reports allocations accurately.

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