pgsql: Remove obsolete IndexIs* macros

Remove obsolete IndexIs* macros

Remove IndexIsValid(), IndexIsReady(), IndexIsLive() in favor of
accessing the index structure directly.  These macros haven't been
used consistently, and the original reason of maintaining source
compatibility with PostgreSQL 9.2 is gone.

Discussion: https://www.postgresql.org/message-id/flat/d419147c-09d4-6196-5d9d-0234b230880a%402ndquadrant.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ae4472c619341ff0517254d395d74796277622e6

Modified Files
--------------
contrib/amcheck/verify_nbtree.c      | 2 +-
contrib/tcn/tcn.c                    | 2 +-
src/backend/access/heap/tuptoaster.c | 2 +-
src/backend/catalog/index.c          | 4 ++--
src/backend/commands/cluster.c       | 4 ++--
src/backend/commands/indexcmds.c     | 4 ++--
src/backend/commands/matview.c       | 2 +-
src/backend/commands/tablecmds.c     | 8 ++++----
src/backend/commands/vacuum.c        | 4 ++--
src/backend/executor/execIndexing.c  | 2 +-
src/backend/optimizer/util/plancat.c | 6 +++---
src/backend/parser/parse_utilcmd.c   | 2 +-
src/backend/utils/cache/relcache.c   | 6 +++---
src/include/catalog/pg_index.h       | 9 ---------
14 files changed, 24 insertions(+), 33 deletions(-)