Much like we did for demo_xcb.h, demo_win32.h now just has the bits for
creating windows and handling events, while demo_d3d12.h has the d3d12
and dxgi bits.
For the build-mingw-32 and build-mingw-64 jobs. These currently end up
picking up Linux pkg-config instead of MinGW pkg-config, which in turn
causes configure to pick up Linux OpenGL and XCB. We happen to get away
with that at the moment because none of the code using HAVE_OPENGL or
HAVE_XCB ends up getting built for Windows, but that's about to change.
Specifically, we'd like to build the vkd3d versions of the demos for
Windows.
All stream output objects need to have a stream index allocated,
whether they are used or not.
We allocate stream outputs here, before other objects are allocated,
because the stream index is needed to create the appropriate output
semantic variables during append_output_copy(), which will be called
in a lowering pass for the Append() method.
It seems that the NVIDIA drivers leaves VBVs bindings untouched
when they are NULL (or the GPU buffer address is NULL), instead of
setting them to a null binding.
Differently from other cases of inconsistent behaviour between AMD
and NVIDIA, here I'm explicitly marking the NVIDIA behaviour as
broken, because the expected behaviour is spelled out explicitly
(at least for the D3D12 specification standards).
