pgsql: Fix printf format string warning on MinGW.

Fix printf format string warning on MinGW.

Commit 517bf2d91 changed a printf format string to placate MinGW, which
at the time warned about "%lld". Current MinGW is now warning about the
replacement "%I64d". Reverting the change clears the warning on the
MinGW CI task, and hopefully it will clear it on build farm animal
fairywren too.

Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reported-by: "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com>
Discussion: https://postgr.es/m/TYAPR01MB5866A71B744BE01B3BF71791F5AEA%40TYAPR01MB5866.jpnprd01.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1319997df92447d9b473a538b109b2d1d560c637

Modified Files
--------------
src/interfaces/ecpg/test/expected/sql-sqlda.c | 137 +++----
src/interfaces/ecpg/test/expected/sql-sqlda.stderr | 450 ++++++++++-----------
src/interfaces/ecpg/test/sql/sqlda.pgc | 9 +-
3 files changed, 293 insertions(+), 303 deletions(-)