pgsql: Add result_types column to pg_prepared_statements view

Add result_types column to pg_prepared_statements view

Containing the types of the columns returned by the prepared
statement.

Prompted by question from IRC user mlvzk.

Author: Dagfinn Ilmari Mannsåker <ilmari(at)ilmari(dot)org>
Discussion: https://www.postgresql.org/message-id/flat/871qwpo7te(dot)fsf(at)wibble(dot)ilmari(dot)org

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/84ad713cf85aeffee5dd39f62d49a1b9e34632da

Modified Files
--------------
doc/src/sgml/catalogs.sgml | 12 ++++++
src/backend/commands/prepare.c | 19 ++++++---
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 6 +--
src/test/regress/expected/prepare.out | 72 +++++++++++++++++------------------
src/test/regress/expected/rules.out | 3 +-
src/test/regress/sql/prepare.sql | 12 +++---
7 files changed, 74 insertions(+), 52 deletions(-)