Blender Git Loki

Remove GHOST API functions for OpenGL offscreen blitting

These were previously used to blit from a offscreen (non-OpenGL)
context, into an onscreen one. We do this differently, and only within
GHOST_XrGraphicsBinding now, so this can be removed.

Refactor OpenGL/DirectX resource sharing for multiple shared resources

Rather than max. one shared resource per DirectX context, code can now
request a handle for a shared resource and ask the DirectX context to do
operations on that.

Fix missing CMake hint for OpenXR SDK path on linux

Windows/deps: Add/fix openxr_sdk dependency

There were a few typos here and there, and the openxr_sdk does not respect the cflags we give it hence a patch was added to work around this undesirable behaviour.

Merge branch 'master' into soc-2019-openxr

Fix compiling with WITH_OPENXR disabled

Blacklist VR add-on in Python tests if WITH_OPENXR is disabled

Expose WITH_OPENXR build option to Python API

Prepare Toggle VR Session operator to be enabled by an add-on

Windows: Print warning and disable `WITH_OPENXR` if SDK is not found

Integrate the OpenXR SDK better into dependency management

Adds the SDK so that `make deps` works, on all platforms. On Windows,
the SDK headers and libraries are now assumed to be in the usual lib
directory.
Also fixes a mistake in install_deps.sh

Note that none of this is tested as it requires an older Visual Studio
version than I have.

Fix compile error on Linux

Merge branch 'master' into soc-2019-openxr

Fix compiling with external OpenXR SDK on Windows

Cleanup: Don't cast away const in GHOST C-API

Fix crash when no OpenXR runtime is found (or setup failed)

Remove bundled OpenXR-SDK sources from extern/

Removes the OPENXR_USE_BUNDLED_SRC option which allowed using the
OpenXR-SDK sources bundled in extern/. It would be too much hassle to
keept these updated.
Now these have to be provided on the system Blender is compiled on. I've
already added necessary bits to install_deps.sh and our Windows
maintainer is ready to provide builds with OpenXR-SDK linked.
Once this gets into master, platform maintainers will have to be
notified about the added dependency.

This also removes the JsonCpp dependency, it was only needed for the
OpenXR-SDK sources.

Linux: Add OpenXR-SDK to install_deps.sh

Silence warnings in OpenXR SDK API layer files

Quiet warning