Gets rid of some mostly duplicated code and adds the ability to do
hardware to hardware transfers.

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

There's enough going on here now that it should not be duplicated
between cuda_device_create and cuda_device_derive.

This commit adds the necessary code to initialize and use a Vulkan device
within the hwcontext libavutil framework.
Currently direct mapping to VAAPI and DRM frames is functional, and
transfers to CUDA and native frames are supported.

Lets hope the future Vulkan video decode extension fits well within this
framework.

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

Similarly to the previous changes, we don't need to synchronise
after a memcpy to device memory. On the other hand, we need to
keep synchronising after a copy to host memory, otherwise there's
no guarantee that subsequent host reads will return valid data.

We have a pattern of wrapping CUDA calls to print errors and
normalise return values that is used in a couple of places. To
avoid duplication and increase consistency, let's put the wrapper
implementation in a shared place and use it everywhere.

Affects:

* avcodec/cuviddec
* avcodec/nvdec
* avcodec/nvenc
* avfilter/vf_scale_cuda
* avfilter/vf_scale_npp
* avfilter/vf_thumbnail_cuda
* avfilter/vf_transpose_npp
* avfilter/vf_yadif_cuda

Regression since ece068a7.
Signed-off-by: Marton Balint <cus@passwd.hu>

Reviewed-by: Timo Rothenpieler <timo@rothenpieler.org>

Signed-off-by: Philip Langdale <philipl@overt.org>

Copied and modified from hwcontext_qsv.c.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

Copied and modified from hwcontext_qsv.c.

CUVID is now capable of returning 10bit and 12bit decoded content
in P010/P016. Let's support transfering those formats.

Signed-off-by: Anton Khirnov <anton@khirnov.net>