Don't suicide on exit status 0.

Don't suicide on exit status 0.

Suiciding when the application exits 0 will cause recovery actions to be
taken.  Usually this is inappropriate.  Only suicide if there is an
explicit AppExit value for 0 in the registry.

Technically such behaviour could be abused to do something like run a
script after successful completion of a service but in most cases a
suicide is undesirable when no actual failure occurred.