set data_size to 0 so that in case we return without setting it nothing funny can happen

Originally committed as revision 7558 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/a52dec.c

@@ -162,6 +162,8 @@ static int a52_decode_frame(AVCodecContext *avctx,
         2, 1, 2, 3, 3, 4, 4, 5
     };
 
+    *data_size= 0;
+
     buf_ptr = buf;
     while (buf_size > 0) {
         len = s->inbuf_ptr - s->inbuf;