Backport a patch from 6.0:

```---------------------------------------------------------
revno: 2599.178.12
revision-id: alik@mysql.com-20080812161845-we7cx9f22yrghob1
committer: Alexander Nozdrin <alik@mysql.com>
branch nick: 6.0-rt-build
timestamp: Tue 2008-08-12 20:18:45 +0400
message:
  Fix memory leak.
```

---------------------------------------------------------

sql/field.h

@@ -2089,7 +2089,7 @@ class Create_field :public Sql_alloc
   A class for sending info to the client
 */
 
-class Send_field {
+class Send_field :public Sql_alloc {
  public:
   const char *db_name;
   const char *table_name,*org_table_name;

sql/sp_head.cc

@@ -2045,7 +2045,7 @@ sp_head::execute_procedure(THD *thd, List<Item> *args)
         break;
       }
 
-      Send_field *out_param_info= new Send_field();
+      Send_field *out_param_info= new (thd->mem_root) Send_field();
       nctx->get_item(i)->make_field(out_param_info);
       out_param_info->db_name= m_db.str;
       out_param_info->table_name= m_name.str;