pgsql: Add cost estimation of range @> and <@ operators.

Add cost estimation of range @> and <@ operators.

The estimates are based on the existing lower bound histogram, and a new
histogram of range lengths.

Bump catversion, because the range length histogram now needs to be present
in statistic slot kind 6, or you get an error on @> and <@ queries. (A
re-ANALYZE would be enough to fix that, though)

Alexander Korotkov, with some refactoring by me.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/59d0bf9dca58b237902c2fd1507e8bc5d54d4a63

Modified Files
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src/backend/utils/adt/rangetypes_selfuncs.c   |  541 ++++++++++++++++++++++++-
src/backend/utils/adt/rangetypes_typanalyze.c |  125 ++++++-
src/include/catalog/catversion.h              |    2 +-
src/include/catalog/pg_operator.h             |    1 +
src/include/catalog/pg_statistic.h            |   12 +-
5 files changed, 667 insertions(+), 14 deletions(-)