* Finalize Event I/O abstraction layer.
* Fix possible fd leakage, Gitlab-CI build and error logging.
* Fixed possible uninitialized signalfd variable.
* Fixed possible memory leak.
* Fixed some SonarCloud complaints.
* Fixed nDPId-test nDPIsrvd-arpa-mockup stuck indefinitely.
* Add nDPId / nDPIsrvd command line option to use poll() on Linux instead of the default epoll().
Signed-off-by: Toni Uhlig <matzeton@googlemail.com>