Intel QSV and OpenCL support

[jchwei]

I found that QtAV now has no qsv and OpenCL support, they are very useful for decode and video render. Compared with PotPlayer, there is a lot of room for improvement.

--- Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/39414189-intel-qsv-and-opencl-support?utm_campaign=plugin&utm_content=tracker%2F307703&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F307703&utm_medium=issues&utm_source=github).