Don't destroy handle not created by use (because the caller will).

(closes issue #18526)
 Reported by: makoto
 Patches: 
       res-config-mysql-include.patch uploaded by makoto (license 38)
 Tested by: makoto


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@300798 65c4cc65-6c06-0410-ace0-fbb531ad65f3

addons/res_config_mysql.c

@@ -978,7 +978,6 @@ static struct ast_config *config_mysql(const char *database, const char *table,
 				if (!ast_config_internal_load(row[2], cfg, config_flags, "", who_asked)) {
 					mysql_free_result(result);
 					release_database(dbh);
-					ast_config_destroy(cfg);
 					return NULL;
 				}
 				continue;