vo_gpu: d3d11: only use presentation feedback with flip model

The current implementation of presentation feedback was designed to be
used with flip model presentation. With the bitblt model,
GetFrameStatistics returns totally different values and it's not clear
if we can use them at all. Previously, this wasn't a problem because
with the bitblt model, GetFrameStatistics only worked in exclusive
fullscreen. Now that mpv supports exclusive fullscreen, we should
explicitly check for a flip model swapchain before using presentation
feedback.

video/out/d3d11/context.c

@@ -258,6 +258,15 @@ static void d3d11_get_vsync(struct ra_swapchain *sw, struct vo_vsync_info *info)
     if (p->opts->sync_interval != 1)
         return;
 
+    // They're also only valid for flip model swapchains
+    DXGI_SWAP_CHAIN_DESC desc;
+    hr = IDXGISwapChain_GetDesc(p->swapchain, &desc);
+    if (FAILED(hr) || (desc.SwapEffect != DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL &&
+                       desc.SwapEffect != DXGI_SWAP_EFFECT_FLIP_DISCARD))
+    {
+        return;
+    }
+
     // GetLastPresentCount returns a sequential ID for the frame submitted by
     // the last call to IDXGISwapChain::Present()
     UINT submit_count;
@@ -308,10 +317,9 @@ static void d3d11_get_vsync(struct ra_swapchain *sw, struct vo_vsync_info *info)
         stats.PresentRefreshCount && stats.SyncRefreshCount &&
         stats.SyncQPCTime.QuadPart)
     {
-        // PresentRefreshCount and SyncRefreshCount might refer to different
-        // frames (this can definitely occur in bitblt-mode.) Assuming mpv
-        // presents on every frame, guess the present count that relates to
-        // SyncRefreshCount.
+        // It's not clear if PresentRefreshCount and SyncRefreshCount can refer
+        // to different frames, but in case they can, assuming mpv presents on
+        // every frame, guess the present count that relates to SyncRefreshCount.
         unsigned expected_sync_pc = stats.PresentCount +
             (stats.SyncRefreshCount - stats.PresentRefreshCount);