avcodec/jpeg2000dec: increase tile_parts to 6

Fixes Ticket4602
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/jpeg2000dec.c

@@ -60,7 +60,7 @@ typedef struct Jpeg2000Tile {
     uint8_t             properties[4];
     Jpeg2000CodingStyle codsty[4];
     Jpeg2000QuantStyle  qntsty[4];
-    Jpeg2000TilePart    tile_part[4];
+    Jpeg2000TilePart    tile_part[6];
     uint16_t tp_idx;                    // Tile-part index
 } Jpeg2000Tile;