libobs-d3d11: Relax minimum Windows for flip model

We'll need flip model swap chains in the future for HDR, and we don't
want to limit HDR to WIndows 11. The new test is the existence of
IDXGIFactory5, which was introduced in Windows 10 1607. This should be
enough for HDR, for which we use APIs in Windows 10 1703.

Hopefully having SetMaximumFrameLatency(40) this time will make enough
of a difference to not bring back reports of degraded performance when
using flip model on Windows 10.

libobs-d3d11/d3d11-subsystem.cpp

@@ -184,40 +184,24 @@ gs_swap_chain::gs_swap_chain(gs_device *device, const gs_init_data *data)
 	  hwnd((HWND)data->window.hwnd),
 	  initData(*data)
 {
-	struct win_version_info ver;
-	get_win_ver(&ver);
-
-	constexpr win_version_info minimum = [] {
-		win_version_info ver{};
-		ver.major = 10;
-		ver.minor = 0;
-		ver.build = 22000;
-		ver.revis = 0;
-		return ver;
-	}();
-
 	DXGI_SWAP_EFFECT effect = DXGI_SWAP_EFFECT_DISCARD;
 	UINT flags = 0;
 
-	if (win_version_compare(&ver, &minimum) >= 0) {
+	ComQIPtr<IDXGIFactory5> factory5 = device->factory;
+	if (factory5) {
 		initData.num_backbuffers = max(data->num_backbuffers, 2);
 
 		effect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
 		flags |= DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;
 
-		ComPtr<IDXGIFactory5> factory5;
-		factory5 = ComQIPtr<IDXGIFactory5>(device->factory);
-		if (factory5) {
-			BOOL featureSupportData = FALSE;
-			const HRESULT hr = factory5->CheckFeatureSupport(
-				DXGI_FEATURE_PRESENT_ALLOW_TEARING,
-				&featureSupportData,
-				sizeof(featureSupportData));
-			if (SUCCEEDED(hr) && featureSupportData) {
-				presentFlags |= DXGI_PRESENT_ALLOW_TEARING;
-
-				flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
-			}
+		BOOL featureSupportData = FALSE;
+		const HRESULT hr = factory5->CheckFeatureSupport(
+			DXGI_FEATURE_PRESENT_ALLOW_TEARING, &featureSupportData,
+			sizeof(featureSupportData));
+		if (SUCCEEDED(hr) && featureSupportData) {
+			presentFlags |= DXGI_PRESENT_ALLOW_TEARING;
+
+			flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
 		}
 	}
 
@@ -1378,8 +1362,7 @@ void device_resize(gs_device_t *device, uint32_t cx, uint32_t cy)
 	}
 
 	try {
-		ID3D11RenderTargetView *renderView = NULL;
-		device->context->OMSetRenderTargets(1, &renderView, NULL);
+		device->context->OMSetRenderTargets(0, NULL, NULL);
 		device->curSwapChain->Resize(cx, cy);
 		device->curFramebufferInvalidate = true;
 	} catch (const HRError &error) {