Make sure that t_ctid is reset to equal t_self in heap_delete and

Make sure that t_ctid is reset to equal t_self in heap_delete and
heap_mark4update; this avoids situations where a deleted tuple might
look like it is chained to something else.  Also, cause all the WAL
redo routines to set t_ctid to equal t_self, rather than leaving it
undefined as before.  Make heap_xlog_clean set the page's LSN and SUI
correctly.  All per past discussions in pghackers, ranging back to
last December.