dsicinav: update bitmap_frame_size, avoid out of array reads.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dsicinav.c

@@ -270,7 +270,7 @@ static int cinvideo_decode_frame(AVCodecContext *avctx,
           cin->bitmap_table[CIN_CUR_BMP], cin->bitmap_size);
         break;
     case 35:
-        cin_decode_huffman(buf, bitmap_frame_size,
+        bitmap_frame_size = cin_decode_huffman(buf, bitmap_frame_size,
           cin->bitmap_table[CIN_INT_BMP], cin->bitmap_size);
         cin_decode_rle(cin->bitmap_table[CIN_INT_BMP], bitmap_frame_size,
           cin->bitmap_table[CIN_CUR_BMP], cin->bitmap_size);