pgsql: Provide query source text when parsing a SQL-standard function b

Provide query source text when parsing a SQL-standard function body.

Without this, we lose error cursor positions, as shown in the
modified regression test result.

Discussion: /messages/by-id/2197698.1617984583@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/409723365b2708acd3bdf2e830257504bdefac4b

Modified Files
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src/backend/commands/functioncmds.c | 10 ++++++++--
src/test/regress/expected/create_function_3.out | 2 ++
2 files changed, 10 insertions(+), 2 deletions(-)