avcodec/pcm: Fix overflow in bitrate computation

Fixes: 129ca3e28d73af7b1e24a9d4118e7a2d/signal_sigabrt_7ffff6ae7cc9_836_762b310fc3ef6087bd7771e5d8e90b9b.asf

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/pcm.c

@@ -47,7 +47,7 @@ static av_cold int pcm_encode_init(AVCodecContext *avctx)
 
     avctx->bits_per_coded_sample = av_get_bits_per_sample(avctx->codec->id);
     avctx->block_align           = avctx->channels * avctx->bits_per_coded_sample / 8;
-    avctx->bit_rate              = avctx->block_align * avctx->sample_rate * 8;
+    avctx->bit_rate              = avctx->block_align * 8LL * avctx->sample_rate;
 
     return 0;
 }