On the latest build @maxbrunsfeld got a panic that hung zed. It appeared
that the hang occured after the minidump had been successfully written,
so our theory on what happened is that the `suspend_all_other_threads`
call in the crash handler suspended the panicking thread (due to the
signal from simulate_exception being received on a different thread),
and then when the crash handler returned everything was suspended so the
panic hook never made it to the `process::abort`.

This change makes the crash handler avoid _both_ the current and the
panicking thread which should avoid that scenario.

Release Notes:

- N/A