Fix planner error with pulling up subquery expressions into function RTEs.
If a function-in-FROM laterally references the output of some sub-SELECT
earlier in the FROM clause, and we are able to flatten that sub-SELECT
into the outer query, the expression(s) copied into the function RTE
missed being processed by eval_const_expressions. This'd lead to trouble
and probable crashes at execution if such expressions contained
named-argument function call syntax or functions with defaulted arguments.
The bug is masked if the query contains any explicit JOIN syntax, which
may help explain why we'd not noticed.
Per bug #17227 from Bernd Dorn. This is an oversight in commit
7266d0997,
so back-patch to v13 where that came in.
Discussion: https://postgr.es/m/17227-
5a28ed1512189fa4@postgresql.org