dcb.c

dcb_write, if write failed, gwbuf wasn't freed.
mysql_backend.c 
	gw_MySQLWrite_backend, if dcb wasn'r in POLLING state then write was skpiped but gwbuf wasn't freed.
mysql_client.c
	gw_MySQLWrite_client, disabled the use of dcb_write because it returns different values than the code it replaced. Also removed erroneous call of gwbuf_consume.
mysql_common.c
	mysql_send_custom_error, removed erroneous call of gwbuf_free.

server/modules/protocol/mysql_client.c

@@ -433,7 +433,7 @@ static int gw_mysql_do_authentication(DCB *dcb, GWBUF *queue) {
 int
 gw_MySQLWrite_client(DCB *dcb, GWBUF *queue)
 {
-#if 1
+#if 0
 	return dcb_write(dcb, queue);
 #else
 int	w, saved_errno = 0;
@@ -762,8 +762,6 @@ int gw_read_client_event(DCB* dcb) {
                                 protocol->state = MYSQL_IDLE;
                         }
                 }
-                /** Free buffer */
-                queue = gwbuf_consume(queue, len);
                 goto return_rc;
         } /*  MYSQL_IDLE */
         break;