mov: Evaluate the movie display matrix

This matrix needs to be applied after all others have (currently only
display matrix from trak), but cannot be handled in movie box, since
streams are not allocated yet. So store it in main context, and apply
it when appropriate, that is after parsing the tkhd one.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavformat/isom.h

@@ -240,6 +240,7 @@ typedef struct MOVContext {
     uint8_t *decryption_key;
     int decryption_key_len;
     int enable_drefs;
+    int32_t movie_display_matrix[3][3]; ///< display matrix from mvhd
 } MOVContext;
 
 int ff_mp4_read_descr_len(AVIOContext *pb);