pgsql: Re-allow INSERT .. ON CONFLICT DO NOTHING on partitioned tables.

Re-allow INSERT .. ON CONFLICT DO NOTHING on partitioned tables.

Commit 8355a011a0124bdf7ccbada206a967d427039553 was reverted in
f05230752d53c4aa74cffa9b699983bbb6bcb118, but this attempt is
hopefully better-considered: we now pass the correct value to
ExecOpenIndices, which should avoid the crash that we hit before.

Amit Langote, reviewed by Simon Riggs and by me. Some final
editing by me.

Discussion: http://postgr.es/m/7ff1e8ec-dc39-96b1-7f47-ff5965dceeac@lab.ntt.co.jp

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/87c37e3291cb75273ccdf4645b9472dd805c4493

Modified Files
--------------
doc/src/sgml/ddl.sgml | 13 +++++++++----
src/backend/commands/copy.c | 3 ++-
src/backend/executor/execPartition.c | 15 ++++++++++-----
src/backend/executor/nodeModifyTable.c | 3 ++-
src/backend/parser/analyze.c | 8 --------
src/include/executor/execPartition.h | 3 ++-
src/test/regress/expected/insert_conflict.out | 13 +++++++++++++
src/test/regress/sql/insert_conflict.sql | 13 +++++++++++++
8 files changed, 51 insertions(+), 20 deletions(-)