pgsql: Move materialized views' is-populated status into their pg_class

Move materialized views' is-populated status into their pg_class entries.

Previously this state was represented by whether the view's disk file had
zero or nonzero size, which is problematic for numerous reasons, since it's
breaking a fundamental assumption about heap storage. This was done to
allow unlogged matviews to revert to unpopulated status after a crash
despite our lack of any ability to update catalog entries post-crash.
However, this poses enough risk of future problems that it seems better to
not support unlogged matviews until we can find another way. Accordingly,
revert that choice as well as a number of existing kluges forced by it
in favor of creating a pg_class.relispopulated flag column.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/1d6c72a55b23554cfb946527dc77f9d80044ae2c

Modified Files
--------------
doc/src/sgml/catalogs.sgml | 14 +++++-
doc/src/sgml/func.sgml | 9 ----
src/backend/catalog/heap.c | 21 +----------
src/backend/catalog/system_views.sql | 2 +-
src/backend/commands/cluster.c | 7 +---
src/backend/commands/createas.c | 11 +++--
src/backend/commands/matview.c | 68 +++++++++++++++++++-------------
src/backend/commands/vacuumlazy.c | 6 ---
src/backend/utils/adt/dbsize.c | 27 -------------
src/backend/utils/cache/relcache.c | 34 ++++------------
src/bin/pg_dump/pg_dump.c | 54 +++++++++++++++++---------
src/bin/pg_dump/pg_dump.h | 2 +-
src/include/catalog/catversion.h | 2 +-
src/include/catalog/heap.h | 1 -
src/include/catalog/pg_class.h | 20 +++++----
src/include/catalog/pg_proc.h | 2 -
src/include/commands/matview.h | 2 +-
src/include/utils/builtins.h | 1 -
src/include/utils/rel.h | 11 ++++-
src/test/regress/expected/matview.out | 18 ++++----
src/test/regress/expected/rules.out | 2 +-
src/test/regress/sql/matview.sql | 6 +-
22 files changed, 141 insertions(+), 179 deletions(-)