pgsql: Don't allocate large buffer on the stack in pg_verifybackup

Don't allocate large buffer on the stack in pg_verifybackup

Per complaint from Andres Freund. Follow his suggestion to allocate the
buffer once in the calling routine instead.

Also make a tiny indentation improvement.

Discussion: /messages/by-id/20240411190147.a3yries632olfcgg@awork3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/929c05774b512bdf7ea4a5912fa2f4d63fc90712

Modified Files
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src/bin/pg_verifybackup/pg_verifybackup.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)