Code review for commit dc203dc3ac40a4b02b92fb827848a547d2957153.

Code review for commit dc203dc3ac40a4b02b92fb827848a547d2957153.

Remove duplicate assignment.  This part by Ashutosh Bapat.

Remove now-obsolete comment.  This part by me, although the pending
join pushdown patch does something similar, and for the same reason:
there's no reason to keep two lists of the things in the fdw_private
structure that have to be kept in sync with each other.