pgsql: Overload index_form_tuple to allow the memory context to be supp

Overload index_form_tuple to allow the memory context to be supplied 40af10b57 changed things so we make use of a generation memory context for storing tuples to be sorted by tuplesort.c. That change does not play nicely with the changes made in 9f03ca915 (back in 2014). That commit changed things

pgsql: Overload index_form_tuple to allow the memory context to be supp

Overload index_form_tuple to allow the memory context to be supplied 40af10b57 changed things so we make use of a generation memory context for storing tuples to be sorted by tuplesort.c. That change does not play nicely with the changes made in 9f03ca915 (back in 2014). That commit changed things