arm64: userspace broken with jemalloc 4.0.0

[Ed Maste]

>> Would you submit a PR for this to keep track of it while the
>> investigation is ongoing?
>
> Andrew provides a patch to fix the problem on the thread. Let me know if
> it's still worth to submit a PR.

No - I wasn't aware that Andrew had all of the details and just wanted
to make sure we had a single place to collect data during the
investigation. Once it turned out that the issue was well-understood
with a patch in progress there was no need.

Thanks,
Ed