parentheses in default

- Adding SHOW CREATE TABLE into all DEFAULT tests,
  to cover need_parentheses_in_default() for all items
- Fixing a few items not to print parentheses in DEFAULT:
  spatial function-alike predicates, IS_IPV4 and IS_IPV6 functions,
  COLUMN_CHECK() and COLUMN_EXISTS().

mysql-test/t/func_encrypt.test

@@ -135,6 +135,7 @@ CREATE TABLE t1 (
   b BLOB DEFAULT DES_ENCRYPT(a, 'passwd'),
   c TEXT DEFAULT DES_DECRYPT(b, 'passwd')
 );
+SHOW CREATE TABLE t1;
 INSERT INTO t1 (a) VALUES ('test');
 SELECT c FROM t1;
 DROP TABLE t1;