Fix inability to reference CYCLE column from inside its CTE.

Such references failed with "cache lookup failed for type 0"
because we didn't resolve the type of the CYCLE column until after
analyzing the CTE's query.  We can just move that processing
to before the recursive parse_sub_analyze call, though.

While here, invent a couple of local variables to make this
code less egregiously wider-than-80-columns.

Per bug #17723 from Vik Fearing.  Back-patch to v14 where
the CYCLE feature was added.

Discussion: https://postgr.es/m/17723-2c4985ff111e7bba@postgresql.org

src/test/regress/expected/with.out

@@ -1221,6 +1221,29 @@ select * from test;
  0 | t        | {(0),(1),(2),(3),(4),(5),(6),(7),(8),(9),(0)}
 (11 rows)
 
+with recursive test as (
+  select 0 as x
+  union all
+  select (x + 1) % 10
+  from test
+    where not is_cycle  -- redundant, but legal
+) cycle x set is_cycle using path
+select * from test;
+ x | is_cycle |                     path                      
+---+----------+-----------------------------------------------
+ 0 | f        | {(0)}
+ 1 | f        | {(0),(1)}
+ 2 | f        | {(0),(1),(2)}
+ 3 | f        | {(0),(1),(2),(3)}
+ 4 | f        | {(0),(1),(2),(3),(4)}
+ 5 | f        | {(0),(1),(2),(3),(4),(5)}
+ 6 | f        | {(0),(1),(2),(3),(4),(5),(6)}
+ 7 | f        | {(0),(1),(2),(3),(4),(5),(6),(7)}
+ 8 | f        | {(0),(1),(2),(3),(4),(5),(6),(7),(8)}
+ 9 | f        | {(0),(1),(2),(3),(4),(5),(6),(7),(8),(9)}
+ 0 | t        | {(0),(1),(2),(3),(4),(5),(6),(7),(8),(9),(0)}
+(11 rows)
+
 -- multiple CTEs
 with recursive
 graph(f, t, label) as (

src/test/regress/sql/with.sql

@@ -605,6 +605,15 @@ with recursive test as (
 ) cycle x set is_cycle using path
 select * from test;
 
+with recursive test as (
+  select 0 as x
+  union all
+  select (x + 1) % 10
+  from test
+    where not is_cycle  -- redundant, but legal
+) cycle x set is_cycle using path
+select * from test;
+
 -- multiple CTEs
 with recursive
 graph(f, t, label) as (