Add documentation on oneway transaction ordering.

     * caller returns immediately, without waiting for a result from the

     * callee. Applies only if the caller and callee are in different

     * processes.

     *

     * <p>The system provides special ordering semantics for multiple oneway calls

     * being made to the same IBinder object: these calls will be dispatched in the

     * other process one at a time, with the same order as the original calls.  These

     * are still dispatched by the IPC thread pool, so may execute on different threads,

     * but the next one will not be dispatched until the previous one completes.  This

     * ordering is not guaranteed for calls on different IBinder objects or when mixing

     * oneway and non-oneway calls on the same IBinder object.</p>

     */

    int FLAG_ONEWAY             = 0x00000001;