avcodec/utils: cast a function argument to shut up a compiler warning

libavcodec/utils.c:251: note: expected ‘const uint8_t *’ but argument is of type ‘const short int *’

libavcodec/utils.c

@@ -1047,7 +1047,8 @@ int attribute_align_arg avcodec_encode_audio(AVCodecContext *avctx,
                                                   avctx->sample_fmt, 1);
         if ((ret = avcodec_fill_audio_frame(frame, avctx->channels,
                                             avctx->sample_fmt,
-                                            samples, samples_size, 1)))
+                                            (const uint8_t *) samples,
+                                            samples_size, 1)))
             return ret;
 
         /* fabricate frame pts from sample count.