gav1_jni: fix pointer->int conversion warnings
gav1_jni: fix pointer->int conversion warnings

fixes:
gav1_jni.cc:446:25: error: cast from pointer to smaller type 'int' loses information
  const int buffer_id = reinterpret_cast<int>(buffer_private_data);
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gav1_jni.cc:730:9: error: cast from pointer to smaller type 'int' loses information
        reinterpret_cast<int>(decoder_buffer->buffer_private_data);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

after https://github.com/google/ExoPlayer/commit/0915998add5918214fa0282a69b50a159168a6d5

PiperOrigin-RevId: 295211245

amzn/exoplayer-amazon-port,ened/ExoPlayer,ened/ExoPlayer,androidx/media,ened/ExoPlayer,google/ExoPlayer,google/ExoPlayer,amzn/exoplayer-amazon-port,androidx/media,amzn/exoplayer-amazon-port,stari4ek/ExoPlayer,stari4ek/ExoPlayer,google/ExoPlayer,stari4ek/ExoPlayer,androidx/media