pgsql: Fix some minor error-checking oversights in ParseFuncOrColumn().

Fix some minor error-checking oversights in ParseFuncOrColumn().

Recent additions to ParseFuncOrColumn to make it reject non-procedure
functions in CALL were neither adequate nor documented. Reorganize
the code to ensure uniform results for all the cases that should be
rejected. Also, use ERRCODE_WRONG_OBJECT_TYPE for this case as well
as the converse case of a procedure in a non-CALL context. The
original coding used ERRCODE_UNDEFINED_FUNCTION which seems wrong,
and is certainly inconsistent with the adjacent wrong-kind-of-routine
errors.

This reorganization also causes the checks for aggregate decoration with
a non-aggregate function to be made in the FUNCDETAIL_COERCION case;
that they were not is a long-standing oversight.

Discussion: https://postgr.es/m/14497.1529089235@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/0dcf68e5a1f1c600bdf29b47cab30a62301a7af1

Modified Files
--------------
src/backend/parser/parse_func.c | 98 +++++++++++++++-----------
src/test/regress/expected/create_procedure.out | 1 +
2 files changed, 57 insertions(+), 42 deletions(-)