pgsql: Fix bogus test for hypothetical indexes in get_actual_variable_r

Fix bogus test for hypothetical indexes in get_actual_variable_range().

That function was supposing that indexoid == 0 for a hypothetical index,
but that is not likely to be true in any non-toy implementation of an index
adviser, since assigning a fake OID is the only way to know at EXPLAIN time
which hypothetical index got selected.  Fix by adding a flag to
IndexOptInfo to mark hypothetical indexes.  Back-patch to 9.0 where
get_actual_variable_range() was added.

Gurjeet Singh

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/7422e0081d04ee4373a822392c729eb892a9d25e

Modified Files
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src/backend/nodes/outfuncs.c         |    2 ++
src/backend/optimizer/util/plancat.c |    1 +
src/backend/utils/adt/selfuncs.c     |    4 ++--
src/include/nodes/relation.h         |    2 ++
4 files changed, 7 insertions(+), 2 deletions(-)