pgsql: Prevent parser from believing that views have system columns.

Prevent parser from believing that views have system columns.

Views should not have any pg_attribute entries for system columns.
However, we forgot to remove such entries when converting a table to a
view. This could lead to crashes later on, if someone attempted to
reference such a column, as reported by Kohei KaiGai.

This problem is corrected properly in HEAD (by removing the pg_attribute
entries during conversion), but in the back branches we need to defend
against existing mis-converted views. This fix costs us an extra syscache
lookup per system column reference, which is annoying but probably not
really measurable in the big scheme of things.

Branch
------
REL8_4_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/67efc03a81a4a34d31545c15533dd78927b8bdb5

Modified Files
--------------
src/backend/parser/parse_relation.c | 11 +++++++++--
src/test/regress/expected/rules.out | 22 ++++++++++++++++++++++
src/test/regress/sql/rules.sql | 15 +++++++++++++++
3 files changed, 46 insertions(+), 2 deletions(-)