message: Fix a crash with D3D11 SWAP_EFFECT_FLIP_DISCARD swapchains. Closes
  * DXGI is entangled with the API unfortunately, such that for D3D11
  DXGI_SWAP_EFFECT_FLIP_DISCARD can only access buffer 0 (like
  DXGI_SWAP_EFFECT_DISCARD) but for D3D12 it can access any buffer. This is
  naturally undocumented.
diff: @@ -365,8 +365,13 @@ void WrappedIDXGISwapChain4::WrapBuffersAfterResize()
  int bufCount = desc.BufferCount;
  - if(desc.SwapEffect == DXGI_SWAP_EFFECT_DISCARD)
  + // discard swap effects only allow querying buffer 0, but only on D3D11 - on D3D12 they can (and
  + // must) still query the full set of buffers.
  + if(m_pDevice->GetFrameCapturer()->GetFrameCaptureDriver() == RDCDriver::D3D11 &&
  + (desc.SwapEffect == DXGI_SWAP_EFFECT_DISCARD || desc.SwapEffect == DXGI_SWAP_EFFECT_FLIP_DISCARD))
  + {
  bufCount = 1;
  + }
  RDCASSERT(bufCount < MAX_NUM_BACKBUFFERS);
  