GiST wal_consistency_checking issue

GiST produces wal_consistency_checking complaints whenever a
XLOG_GIST_DELETE record is replayed. The immediate problem is that
F_TUPLES_DELETED is set (set, *not* unset) within
gistRedoDeleteRecord, even though we do nothing with XLOG_GIST_DELETE
at the corresponding point of original execution, in gistprunepage.
The more fundamental problem is that we're using F_TUPLES_DELETED for
anything at all.

The purpose of XLOG_GIST_DELETE relates in some way to old style
VACUUM FULL. It's obviously useless now: there are 3 places that set
F_TUPLES_DELETED, but nothing ever tests whether it is set in any GiST
page's opaque area's flags field (barring pageinspect).

Attached patch marks F_TUPLES_DELETED deprecated, removes all of its
helper function-style macros, and removes all remaining callers of
those macros.

--
Peter Geoghegan