There is a bug when external program *startup* does not return "OK". This
can also lead to a misadressing with potentially a segfault (very unlikely).
Note that no problem exists once the initializiation phase of the external
program is finished and regular message transfer runs.
The problem basically is that for a startup failure, the control data for
that external program instance is freed on error. Unfortunately, that state
data is needed later on to detect a suspended instance. We now keep the control
data even on init failure (as we then need to do normal control options).
closes https://github.com/rsyslog/rsyslog/issues/4967