pgsql: Don't reject ROW_MARK_REFERENCE rowmarks for materialized views.

Don't reject ROW_MARK_REFERENCE rowmarks for materialized views.

We should allow this so that matviews can be referenced in UPDATE/DELETE
statements in READ COMMITTED isolation level.  The requirement for that
is that a re-fetch by TID will see the same row version the query saw
earlier, which is true of matviews, so there's no reason for the
restriction.  Per bug #9398.

Michael Paquier, after a suggestion by me

Branch
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REL9_3_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/3973034e6dc599de2203ed812f783a57b63dce5c

Modified Files
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src/backend/executor/execMain.c       |   13 +++++++------
src/test/regress/expected/matview.out |   26 ++++++++++++++++++++++++++
src/test/regress/sql/matview.sql      |    8 ++++++++
3 files changed, 41 insertions(+), 6 deletions(-)