Make fast_default regression tests locale independent

src/test/regress/expected/fast_default.out

@@ -339,7 +339,7 @@ ORDER BY pk LIMIT 10;
 (10 rows)
 
 -- Aggregate function
-SELECT SUM(c_bigint), MAX(c_text), MIN(c_text) FROM T;
+SELECT SUM(c_bigint), MAX(c_text COLLATE "C" ), MIN(c_text COLLATE "C") FROM T;
  sum |  max  | min 
 -----+-------+-----
  200 | hello | 31

src/test/regress/sql/fast_default.sql

@@ -290,7 +290,7 @@ FROM T
 ORDER BY pk LIMIT 10;
 
 -- Aggregate function
-SELECT SUM(c_bigint), MAX(c_text), MIN(c_text) FROM T;
+SELECT SUM(c_bigint), MAX(c_text COLLATE "C" ), MIN(c_text COLLATE "C") FROM T;
 
 -- ORDER BY
 SELECT * FROM T ORDER BY c_bigint, c_text, pk LIMIT 10;