should be 'RangeTblEntry' ; explain.c had copied the erroneous code.

This probably ought to be kept in *all* the port files, but these two
are the only ones that generated compiler warnings for me ...

from Andreas Z.; minor cosmetic cleanups.

creates a reduce/reduce conflict, which I resolved by changing the
'AexprConst -> Typename Sconst' rule to 'AexprConst -> SimpleTypename Sconst'.
In other words, a subscripted type declaration can't be used in that
syntax any longer.  This seems a small price to pay for not having to
qualify subscripted columns anymore.
Other cleanups: rename res_target_list to update_target_list, and remove
productions for variants that are not legal in an UPDATE target list;
rename res_target_list2 to plain target_list; delete position_expr
in favor of using b_expr in that production; merge opt_indirection
into attr nonterminal, since there are no places where an unsubscripted
attr is wanted; fix typos in Param support; change case_arg so that
an arbitrary a_expr is allowed, not only a column name.

care of equal-key cases, eliminating bt_firsteq().  The linear search
formerly done by bt_firsteq() took a lot of time in the case where many
equal keys appear on the same page.

Fix synopsis info thanks to Yves.Martin@ensimag.imag.fr.