- The function destroy_global_config was called from normal_exit even
  if init_global_config hadn't been called before, such as when ltrace
  was run with no command line arguments.  This led to crashes.  We
  avoided similar crashes due to exit from init_global_config by
  calling _Exit instead.

- Instead, schedule execution of destroy_global_config only after it
  is known that init_global_config was successful.  Replace the clumsy
  _Exit calls again by plain exit.