pgsql: Make some xlogreader messages more accurate

Make some xlogreader messages more accurate

When you have some invalid WAL, you often get a message like "wanted
24, got 0". This is a bit incorrect, since it really wanted *at
least* 24, not exactly 24. This updates the messages to that effect,
and also adds that detail to one message where it was available but
not printed.

Reviewed-by: Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>
Reviewed-by: Jeevan Ladhe <jeevanladhe(dot)os(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/726d782b-5e45-0c3e-d775-6686afe9aa83%40enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/4ac30ba4f29d4b586b131404b0d514f16501272a

Modified Files
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src/backend/access/transam/xlogreader.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)