Provide the same debugging opportunities for api_fatal() as we do for a
core-dumping signal:
1) Break into any attached debugger
2) Start JIT debugger (if configured) (keeping these under DEBUGGING doesn't seem helpful)
3) Write a coredump (if rlim_core > 1MB)
4) Write a stackdump (if that failed, or 0 < rlim_core <= 1MB)
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