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.rupireddyforpostgres@gmail.com>
Reviewed-by: Jeevan Ladhe <jeevanladhe.os@gmail.com>
Discussion: /messages/by-id/726d782b-5e45-0c3e-d775-6686afe9aa83@enterprisedb.com

Branch
------
master

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

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