nvidia capture sdk support

[Antoine Martin]

Split from #365: the nvidia documentation is finally available: ​NVIDIA Capture SDK.

We could use this for high performance shadow servers or with stereo rendering, especially for win32 (#389) where this solves the biggest problem (efficient pixel capture).

[Antoine Martin]

See also #1347 and #1308

[Antoine Martin]

Problem is that the SDK states: NVIDIA Quadro 2000 class or higher, select Tesla including M6/M60/M10 and P40.
And sure enough, I tried on on both Linux and MS Windows 7, no go with a GTX 1070 / GTX 970. Looks like a purely commercial licensing restriction, again.

We probably need a Quadro Maxwell or newer to be able to do capture at 4k to HEVC, and those cards aren't cheap: ​M4000 costs ~$800.
The ​M2000 is a bit cheaper at $420, but for our purpose the performance will be similar to my old GTX 750 Ti... which costs $100, sigh.

For non-proprietary options, see ticket:389#comment:19

A good explanation of the differences between NvFBC, NvIFR, NvENC:​Steam : Explanation NvFBC, NvIFR, NvENC.

[Antoine Martin]

Recorded some progress here: ticket:389#comment:21.
Needs porting to Linux.

[Antoine Martin]

Partial port to Linux done in r15787.
(CUDA variant still needs doing, will be useful for toying with GPU pre-compression)

[Antoine Martin]

pkg-config file used on Linux

[Antoine Martin]

pkgconfig file to use on MS Windows

[Antoine Martin]

RPM packaging fix in r15941 so users without the nvidia proprietary drivers can still install the package!

before:

$ rpm -qpR ./RPMS/x86_64/python2-xpra-2.1-0.fc26.x86_64.rpm  | grep -i nvidia
libnvidia-fbc.so.1()(64bit)

and after:

$ rpm -qpR ./RPMS/x86_64/python2-xpra-2.1-0.fc26.x86_64.rpm  | grep -i nvidia