pgsql: Support min/max index optimizations on boolean columns.

Support min/max index optimizations on boolean columns.

Since bool_and() is equivalent to min(), and bool_or() to max(), we might
as well let them be index-optimized in the same way. The practical value
of this is debatable at best, but it seems nearly cost-free to enable it.
Code-wise, we need only adjust the entries in pg_aggregate. There is a
measurable planning speed penalty for a query involving one of these
aggregates, but it is only a few percent in simple cases, so that seems
acceptable.

Marti Raudsepp, reviewed by Abhijit Menon-Sen

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/cbba55d6d792b55f6b448a31fc14aef84510967c

Modified Files
--------------
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_aggregate.h | 6 +++---
src/test/regress/expected/opr_sanity.out | 30 ++++++++++++++++++------------
src/test/regress/sql/opr_sanity.sql | 4 ++--
4 files changed, 24 insertions(+), 18 deletions(-)