Fix bogus handling of "postponed" lateral quals.

When pulling a "postponed" qual from a LATERAL subquery up into the quals
of an outer join, we must make sure that the postponed qual is included
in those seen by make_outerjoininfo().  Otherwise we might compute a
too-small min_lefthand or min_righthand for the outer join, leading to
"JOIN qualification cannot refer to other relations" failures from
distribute_qual_to_rels.  Subtler errors in the created plan seem possible,
too, if the extra qual would only affect join ordering constraints.

Per bug #9041 from David Leverton.  Back-patch to 9.3.

src/test/regress/expected/join.out

@@ -4012,6 +4012,28 @@ select c.*,a.*,ss1.q1,ss2.q1,ss3.* from
                Output: i.f1
 (34 rows)
 
+-- check processing of postponed quals (bug #9041)
+explain (verbose, costs off)
+select * from
+  (select 1 as x) x cross join (select 2 as y) y
+  left join lateral (
+    select * from (select 3 as z) z where z.z = x.x
+  ) zz on zz.z = y.y;
+                  QUERY PLAN                  
+----------------------------------------------
+ Nested Loop Left Join
+   Output: (1), (2), (3)
+   Join Filter: (((3) = (1)) AND ((3) = (2)))
+   ->  Nested Loop
+         Output: (1), (2)
+         ->  Result
+               Output: 1
+         ->  Result
+               Output: 2
+   ->  Result
+         Output: 3
+(11 rows)
+
 -- test some error cases where LATERAL should have been used but wasn't
 select f1,g from int4_tbl a, (select f1 as g) ss;
 ERROR:  column "f1" does not exist

src/test/regress/sql/join.sql

@@ -1120,6 +1120,14 @@ select c.*,a.*,ss1.q1,ss2.q1,ss3.* from
   ) on c.q2 = ss2.q1,
   lateral (select * from int4_tbl i where ss2.y > f1) ss3;
 
+-- check processing of postponed quals (bug #9041)
+explain (verbose, costs off)
+select * from
+  (select 1 as x) x cross join (select 2 as y) y
+  left join lateral (
+    select * from (select 3 as z) z where z.z = x.x
+  ) zz on zz.z = y.y;
+
 -- test some error cases where LATERAL should have been used but wasn't
 select f1,g from int4_tbl a, (select f1 as g) ss;
 select f1,g from int4_tbl a, (select a.f1 as g) ss;