GitLab

Fix some part of update of old-style coordinates in parallel replication:

 - Ignore XtraDB request for old-style coordinates, not meaningful for
   parallel replication (must use GTID to get crash-safe parallel slave).

 - Only update relay log coordinates forward, not backwards, to ensure
   that parallel threads do not conflict with each other.

 - Move future_event_relay_log_pos to rgi.