Copy some assertions from _bt_form_posting() to its sibling function,
_bt_update_posting().
Discussion: https://postgr.es/m/CAH2-WzkPR8KMwkL0ap976kmXwBCeukTeHz6fB-U__wvuP1S9Zg@mail.gmail.com
else
newsize = keysize;
+ Assert(newsize <= INDEX_SIZE_MASK);
+ Assert(newsize == MAXALIGN(newsize));
+
/* Allocate memory using palloc0() (matches index_form_tuple()) */
itup = palloc0(newsize);
memcpy(itup, origtuple, keysize);
Assert(ui == nhtids);
Assert(d == vacposting->ndeletedtids);
Assert(nhtids == 1 || _bt_posting_valid(itup));
+ Assert(nhtids > 1 || ItemPointerIsValid(&itup->t_tid));
/* vacposting arg's itup will now point to updated version */
vacposting->itup = itup;