delete redundant code

src/sql/parser/gen_type_name.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 echo -e '#include "objit/common/ob_item_type.h"'
 echo -e "const char* get_type_name(int type)\n{"
 echo -e "\tswitch(type){"