pgsql: Revert "Catalog NOT NULL constraints" and fallout

Revert "Catalog NOT NULL constraints" and fallout

This reverts commit e056c557aef4 and minor later fixes thereof.

There's a few problems in this new feature -- most notably regarding
pg_upgrade behavior, but others as well.  This new feature is not in any
way critical on its own, so instead of scrambling to fix it we revert it
and try again in early 17 with these issues in mind.

Discussion: https://postgr.es/m/3801207.1681057430@sss.pgh.pa.us

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/9ce04b50e120275afbc03ca0b80839dde3da8308

Modified Files
--------------
doc/src/sgml/catalogs.sgml                         |    1 -
doc/src/sgml/ref/alter_table.sgml                  |   14 +-
doc/src/sgml/ref/create_table.sgml                 |    8 +-
src/backend/catalog/heap.c                         |  491 ++------
src/backend/catalog/pg_constraint.c                |   97 --
src/backend/commands/tablecmds.c                   | 1326 +++++---------------
src/backend/nodes/outfuncs.c                       |    4 -
src/backend/nodes/readfuncs.c                      |    8 +-
src/backend/optimizer/util/plancat.c               |    2 -
src/backend/parser/gram.y                          |   13 -
src/backend/parser/parse_utilcmd.c                 |  206 +--
src/backend/utils/adt/ruleutils.c                  |   14 -
src/bin/pg_dump/common.c                           |   15 +-
src/bin/pg_dump/pg_backup_archiver.c               |    2 -
src/bin/pg_dump/pg_dump.c                          |  209 +--
src/bin/pg_dump/pg_dump.h                          |    2 +-
src/bin/pg_dump/t/002_pg_dump.pl                   |    6 +-
src/include/catalog/catversion.h                   |    2 +-
src/include/catalog/heap.h                         |    7 +-
src/include/catalog/pg_constraint.h                |   11 +-
src/include/commands/tablecmds.h                   |    2 -
src/include/nodes/parsenodes.h                     |   14 +-
.../test_ddl_deparse/expected/alter_table.out      |   18 +-
.../test_ddl_deparse/expected/create_table.out     |   25 +-
.../modules/test_ddl_deparse/test_ddl_deparse.c    |    4 -
src/test/regress/expected/alter_table.out          |   50 +-
src/test/regress/expected/cluster.out              |    7 +-
src/test/regress/expected/constraints.out          |  114 --
src/test/regress/expected/create_table.out         |   27 +-
src/test/regress/expected/event_trigger.out        |    2 -
src/test/regress/expected/foreign_data.out         |   11 +-
src/test/regress/expected/foreign_key.out          |   16 +-
src/test/regress/expected/indexing.out             |   41 +-
src/test/regress/expected/inherit.out              |  408 ------
src/test/regress/expected/replica_identity.out     |   13 -
src/test/regress/parallel_schedule                 |    3 +-
src/test/regress/sql/alter_table.sql               |   26 +-
src/test/regress/sql/constraints.sql               |   43 -
src/test/regress/sql/create_table.sql              |    6 +-
src/test/regress/sql/indexing.sql                  |    8 +-
src/test/regress/sql/inherit.sql                   |  211 ----
src/test/regress/sql/replica_identity.sql          |   12 -
42 files changed, 625 insertions(+), 2874 deletions(-)