nellymoser: use constant seed for dithering RNG

Originally committed as revision 20658 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/nellymoserdec.c

@@ -129,7 +129,7 @@ static av_cold int decode_init(AVCodecContext * avctx) {
     NellyMoserDecodeContext *s = avctx->priv_data;
 
     s->avctx = avctx;
-    av_lfg_init(&s->random_state, ff_random_get_seed());
+    av_lfg_init(&s->random_state, 0);
     ff_mdct_init(&s->imdct_ctx, 8, 1, 1.0);
 
     dsputil_init(&s->dsp, avctx);