replicate_events_marked_for_skip=FILTER_ON_MASTER

When events of a big transaction are binlogged offsetting over 2GB from
the beginning of the log the semisync master's dump thread
lost such events.
The events were skipped by the Dump thread that found their skipping
status erroneously.

The current fixes make sure the skipping status is computed correctly.
The test verifies them simulating the 2GB offset.