pgsql: Rename a function to avoid naming conflict in parallel regressio

Rename a function to avoid naming conflict in parallel regression tests.

Commit 31a891857a128828d47d93c63e041f3b69cbab70 added some tests in
plpgsql.sql that used a function rather unthinkingly named "foo()".
However, rangefuncs.sql has some much older tests that create a function
of that name, and since these test scripts run in parallel, there is a
chance of failures if the timing is just right. Use another name to
avoid that. Per buildfarm (failure seen today on "hamerkop", but
probably it's happened before and not been noticed).

Branch
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REL9_3_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/e407192c937d993be1a4f5636a1afa57cf492f6f

Modified Files
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src/test/regress/expected/plpgsql.out | 72 ++++++++++++++++-----------------
src/test/regress/sql/plpgsql.sql | 56 ++++++++++++-------------
2 files changed, 64 insertions(+), 64 deletions(-)