Make regression test output stable.

In the test query I added for ALTER TABLE retaining comments, the order of
the result rows was not stable, and varied across systems. Add an ORDER BY
to make the order predictable. This should fix the buildfarm failures.

src/test/regress/expected/alter_table.out

@@ -2418,14 +2418,14 @@ SELECT col_description('comment_test'::regclass, 1) as comment;
  Column 'id' on comment_test
 (1 row)
 
-SELECT indexrelid::regclass as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass;
+SELECT indexrelid::regclass::text as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass ORDER BY 1, 2;
        index        |                    comment                    
 --------------------+-----------------------------------------------
  comment_test_index | Simple index on comment_test
  comment_test_pk    | Index backing the PRIMARY KEY of comment_test
 (2 rows)
 
-SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass;
+SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass ORDER BY 1, 2;
            constraint            |                    comment                    
 ---------------------------------+-----------------------------------------------
  comment_test_pk                 | PRIMARY KEY constraint of comment_test
@@ -2449,18 +2449,18 @@ SELECT col_description('comment_test'::regclass, 1) as comment;
  Column 'id' on comment_test
 (1 row)
 
-SELECT indexrelid::regclass as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass;
+SELECT indexrelid::regclass::text as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass ORDER BY 1, 2;
        index        |                    comment                    
 --------------------+-----------------------------------------------
- comment_test_pk    | Index backing the PRIMARY KEY of comment_test
  comment_test_index | Simple index on comment_test
+ comment_test_pk    | Index backing the PRIMARY KEY of comment_test
 (2 rows)
 
-SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass;
+SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass ORDER BY 1, 2;
            constraint            |                    comment                    
 ---------------------------------+-----------------------------------------------
- comment_test_positive_col_check | CHECK constraint on comment_test.positive_col
  comment_test_pk                 | PRIMARY KEY constraint of comment_test
+ comment_test_positive_col_check | CHECK constraint on comment_test.positive_col
 (2 rows)
 
 -- Check that we map relation oids to filenodes and back correctly.  Only

src/test/regress/sql/alter_table.sql

@@ -1610,8 +1610,8 @@ COMMENT ON CONSTRAINT comment_test_pk ON comment_test IS 'PRIMARY KEY constraint
 COMMENT ON INDEX comment_test_pk IS 'Index backing the PRIMARY KEY of comment_test';
 
 SELECT col_description('comment_test'::regclass, 1) as comment;
-SELECT indexrelid::regclass as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass;
-SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass;
+SELECT indexrelid::regclass::text as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass ORDER BY 1, 2;
+SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass ORDER BY 1, 2;
 
 -- Change the datatype of all the columns. ALTER TABLE is optimized to not
 -- rebuild an index if the new data type is binary compatible with the old
@@ -1626,8 +1626,8 @@ ALTER TABLE comment_test ALTER COLUMN positive_col SET DATA TYPE bigint;
 
 -- Check that the comments are intact.
 SELECT col_description('comment_test'::regclass, 1) as comment;
-SELECT indexrelid::regclass as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass;
-SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass;
+SELECT indexrelid::regclass::text as index, obj_description(indexrelid, 'pg_class') as comment FROM pg_index where indrelid = 'comment_test'::regclass ORDER BY 1, 2;
+SELECT conname as constraint, obj_description(oid, 'pg_constraint') as comment FROM pg_constraint where conrelid = 'comment_test'::regclass ORDER BY 1, 2;
 
 
 -- Check that we map relation oids to filenodes and back correctly.  Only