This catches up with the recent renaming of all user-facing mentions
of "xlog" to "wal".
Discussion: https://www.postgresql.org/message-id/flat/
20181129084708.GA9562%40msg.credativ.de
(flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "",
(flags & CHECKPOINT_FORCE) ? " force" : "",
(flags & CHECKPOINT_WAIT) ? " wait" : "",
- (flags & CHECKPOINT_CAUSE_XLOG) ? " xlog" : "",
+ (flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "",
(flags & CHECKPOINT_CAUSE_TIME) ? " time" : "",
(flags & CHECKPOINT_FLUSH_ALL) ? " flush-all" : "");
}