wavpackenc: fix number of samples per block

Currently, the encoder will try to reduce it down to 150000, but the
decoder will complain starting at 131072 (WV_MAX_SAMPLES). Therefore,
change the loop limit.

Fixes ticket #3881.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/wavpackenc.c

@@ -135,7 +135,7 @@ static av_cold int wavpack_encode_init(AVCodecContext *avctx)
         else
             block_samples = avctx->sample_rate;
 
-        while (block_samples * avctx->channels > 150000)
+        while (block_samples * avctx->channels > WV_MAX_SAMPLES)
             block_samples /= 2;
 
         while (block_samples * avctx->channels < 40000)