pgsql: Extend index AM API for parallel index scans.

Extend index AM API for parallel index scans.

This patch doesn't actually make any index AM parallel-aware, but it
provides the necessary functions at the AM layer to do so.

Rahila Syed, Amit Kapila, Robert Haas

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/7b4ac19982a77a1a2a6f096c4a11ee7325a14d2c

Modified Files
--------------
contrib/bloom/blutils.c | 3 +
doc/src/sgml/indexam.sgml | 67 +++++++++++++++++
src/backend/access/brin/brin.c | 3 +
src/backend/access/gin/ginutil.c | 3 +
src/backend/access/gist/gist.c | 3 +
src/backend/access/hash/hash.c | 3 +
src/backend/access/index/indexam.c | 135 +++++++++++++++++++++++++++++++++--
src/backend/access/nbtree/nbtree.c | 3 +
src/backend/access/spgist/spgutils.c | 3 +
src/include/access/amapi.h | 17 +++++
src/include/access/genam.h | 9 +++
src/include/access/relscan.h | 13 ++++
src/include/c.h | 3 +
src/tools/pgindent/typedefs.list | 2 +
14 files changed, 262 insertions(+), 5 deletions(-)