pgsql: Even if some partitions are foreign, allow tuple routing.

Even if some partitions are foreign, allow tuple routing.

This doesn't allow routing tuple to the foreign partitions themselves,
but it permits tuples to be routed to regular partitions despite the
presence of foreign partitions in the same inheritance hierarchy.

Etsuro Fujita, reviewed by Amit Langote and by me.

Discussion: http://postgr.es/m/bc3db4c1-1693-3b8a-559f-33ad2b50b7ad@lab.ntt.co.jp

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9d71323daca412e6e175595e1e42809fb5e1172d

Modified Files
--------------
contrib/file_fdw/input/file_fdw.source | 21 +++++++++
contrib/file_fdw/output/file_fdw.source | 81 +++++++++++++++++++++++++++++++++
src/backend/executor/execMain.c | 25 ++++++----
src/backend/executor/nodeModifyTable.c | 2 +-
src/include/executor/executor.h | 2 +-
5 files changed, 120 insertions(+), 11 deletions(-)