more data_size=0 cleanup

Originally committed as revision 3147 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mdec.c

@@ -163,8 +163,6 @@ static int decode_frame(AVCodecContext *avctx,
     AVFrame * const p= (AVFrame*)&a->picture;
     int i;
 
-    *data_size = 0;
-
     /* special case for last picture */
     if (buf_size == 0) {
         return 0;

libavcodec/pcm.c

@@ -334,7 +334,6 @@ static int pcm_decode_frame(AVCodecContext *avctx,
         }
         break;
     default:
-        *data_size = 0;
         return -1;
     }
     *data_size = (uint8_t *)samples - (uint8_t *)data;