turing.exe decode does not honor -- frames CL switch

How to reproduce : turing.exe decode **--frames 1** c:\foo.hevc
Observed behavior:  decoding is keep going even after 1 frame/picture has been decoded

It seems there is no call to `StateDecode::stop()` (I guess it should be called once in a while during the decode loop)

```
bool stop() const
{
    return this->maxPictures != 0 && this->n == this->maxPictures;
}

```