pgsql: Remove nbtree BTreeTupleSetAltHeapTID() function.

Remove nbtree BTreeTupleSetAltHeapTID() function.

Since heap TID is supposed to be just another key attribute to the
implementation, it doesn't make much sense to have separate
BTreeTupleSetNAtts() and BTreeTupleSetAltHeapTID() functions.  Merge the
two functions together.  This slightly simplifies _bt_truncate().

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/60cbd7751c1ec6ffdf2ffc520ddeb35cb2f2ed70

Modified Files
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src/backend/access/nbtree/nbtinsert.c |  4 ++--
src/backend/access/nbtree/nbtsort.c   |  4 ++--
src/backend/access/nbtree/nbtutils.c  | 10 ++++++----
src/include/access/nbtree.h           | 36 ++++++++++++++++-------------------
4 files changed, 26 insertions(+), 28 deletions(-)