Clean up object data in regex and zlibw modules

See commit messages for more details.

The branch passed make check except for
queue-persist.sh (passed on rerun)
udp-msgreduc-vg.sh
udp-msgreduc-orgmsg-vg.sh

Log files of both tests contain these messages:
rsyslogd 8.7.0.master error: invalid debug option '', value 'nologfuncflow' - ignored
rsyslogd 8.7.0.master error: invalid debug option '', value 'noprintmutexaction' - ignored