If exiting using _Exit or ExitProcess, DLLs are still unloaded
cleanly before exiting, running destructors and other cleanup in those
DLLs. When the caller expects to exit without cleanup, running
destructors in some loaded DLLs (which can be either libLLVM.dll or
e.g. libc++.dll) can cause deadlocks occasionally.
This is an alternative to D102684.