pgsql: Add checkpoint and REDO LSN to log_checkpoints message.

Add checkpoint and REDO LSN to log_checkpoints message.

It is useful for debugging purposes to report the checkpoint LSN and
REDO LSN in log_checkpoints message. It can give more context while
analyzing checkpoint-related issues. pg_controldata reports the last
checkpoint LSN and REDO LSN, but having this information alongside
the log message helps analyze issues that happened previously,
connect the dots and identify the root cause.

Author: Bharath Rupireddy, Kyotaro Horiguchi
Reviewed-by: Michael Paquier, Julien Rouhaud, Nathan Bossart, Fujii Masao, Greg Stark
Discussion: https://postgr.es/m/CALj2ACWt6kqriAHrO+AJj+OmP=suwbktHT5JoYAn-nqZe2gd2g@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/62c46eee2279eb0300ab7ffe393d0d0dcfafb157

Modified Files
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src/backend/access/transam/xlog.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)