pgsql: Mop-up for AIX-ectomy: remove now-dead test code.

Mop-up for AIX-ectomy: remove now-dead test code.

Commit 0b16bb877 removed the test query added by commit 79b716cfb,
but not the C-language support function used by that query.  I don't
see any plausible reason why we'd need that function again, so throw
it overboard too.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f0827b443e6014a9d9fdcdd099603576154a3733

Modified Files
--------------
src/test/regress/expected/test_setup.out |  4 ----
src/test/regress/regress.c               | 41 --------------------------------
src/test/regress/sql/test_setup.sql      |  5 ----
3 files changed, 50 deletions(-)