pgsql: Remove some unused and seldom used fields from RelationAmInfo.

Remove some unused and seldom used fields from RelationAmInfo.

This saves some memory from each index relcache entry. At least on a 64-bit
machine, it saves just enough to shrink a typical relcache entry's memory
usage from 2k to 1k. That's nice if you have a lot of backends and a lot of
indexes.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/87ae9e72654ddddf25433b8a178e9268cf03f5b5

Modified Files
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src/backend/access/index/indexam.c |   19 +++++++++++++------
src/include/utils/rel.h            |   10 ++--------
2 files changed, 15 insertions(+), 14 deletions(-)