VC-1 interlaced B-frames support

Hello,

This patch updates the VC-1 related files from ffmpeg 0.10.6 close to the ffmpeg master versions. Currently the B-frames are missing when playing VC-1 interlaced content. With this patch the B-frames are added when using hardware acceleration. For software decoding B-frames still don't show because the ffmpeg support for this is not complete.

This patch does not solve the blocking artefacts which currently show with some VC-1 interlaced content.

I myself only tested it with XVBA acceleration and software decoding. I think it is good to test it on some other hardware configurations before commiting it in the master branch.

This is my first pull request so I hope everything is in order. Feedback is welcome.

Edit: The first and last commit are unnecessary. The last commit removes the first commit changes. I expected these not to show up in the pull request. First lesson learned.