Without this change, when e.g. event_timeout= is specified in udev.conf,
udevadm and friends which loads udev.conf warn about unknown key:
===
$ udevadm info /sys/class/net/lo
/run/udev/udev.conf.d/test-17.conf:1: Unknown key 'event_timeout', ignoring.
/run/udev/udev.conf.d/test-17.conf:2: Unknown key 'timeout_signal', ignoring.
===