pgsql: Remove direct uses of ItemPointer.{ip_blkid,ip_posid}

Remove direct uses of ItemPointer.{ip_blkid,ip_posid}

There are no functional changes here; this simply encapsulates knowledge
of the ItemPointerData struct so that a future patch can change things
without more breakage.

All direct users of ip_blkid and ip_posid are changed to use existing
macros ItemPointerGetBlockNumber and ItemPointerGetOffsetNumber
respectively.  For callers where that's inappropriate (because they
Assert that the itempointer is is valid-looking), add
ItemPointerGetBlockNumberNoCheck and ItemPointerGetOffsetNumberNoCheck,
which lack the assertion but are otherwise identical.

Author: Pavan Deolasee
Discussion: https://postgr.es/m/CABOikdNnFon4cJiL=h1mZH3bgUeU+sWHuU4Yr8AB=j3A2p1GiA@mail.gmail.com

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/ce96ce60ca2293f75f36c3661e4657a3c79ffd61

Modified Files
--------------
contrib/pageinspect/btreefuncs.c                |  4 ++--
contrib/pgstattuple/pgstattuple.c               |  2 +-
src/backend/access/gin/ginget.c                 | 29 +++++++++++++++----------
src/backend/access/gin/ginpostinglist.c         | 14 +++++-------
src/backend/replication/logical/reorderbuffer.c |  4 ++--
src/backend/storage/page/itemptr.c              | 15 +++++++------
src/backend/utils/adt/tid.c                     | 17 +++++----------
src/include/access/gin_private.h                |  6 ++---
src/include/access/ginblock.h                   | 11 ++++++++--
src/include/access/htup_details.h               |  2 +-
src/include/access/nbtree.h                     |  5 ++---
src/include/storage/itemptr.h                   | 26 ++++++++++++++++++----
12 files changed, 78 insertions(+), 57 deletions(-)