pgsql: Remove the SECURITY_ROW_LEVEL_DISABLED security context bit.

Remove the SECURITY_ROW_LEVEL_DISABLED security context bit.

This commit's parent made superfluous the bit's sole usage.  Referential
integrity checks have long run as the subject table's owner, and that
now implies RLS bypass.  Safe use of the bit was tricky, requiring
strict control over the SQL expressions evaluating therein.  Back-patch
to 9.5, where the bit was introduced.

Based on a patch by Stephen Frost.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7f11724bd61b420acb2839908d51674e86e52034

Modified Files
--------------
src/backend/utils/adt/ri_triggers.c |   17 +----------------
src/backend/utils/cache/plancache.c |   12 ++----------
src/backend/utils/init/miscinit.c   |   14 +-------------
src/backend/utils/misc/rls.c        |    7 -------
src/include/miscadmin.h             |    2 --
src/include/utils/plancache.h       |    1 -
6 files changed, 4 insertions(+), 49 deletions(-)