another silly typo which surprisingly neither valgrind nor cmp of the file output cought

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@6100 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/mpegaudiodec.c

@@ -1673,7 +1673,7 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
         vlc = &huff_vlc[l];
 
         if(!l){
-            memset(&g->sb_hybrid[s_index], 0, sizeof(*g->sb_hybrid)*j);
+            memset(&g->sb_hybrid[s_index], 0, sizeof(*g->sb_hybrid)*2*j);
             s_index += 2*j;
             continue;
         }