WindowInfo: Don't clear display when going surfaceless

Fixes panic when a popup occurs when using GLX.

src/frontend-common/d3d12_host_display.cpp

@@ -348,6 +348,8 @@ bool D3D12HostDisplay::ChangeRenderWindow(const WindowInfo& new_wi)
 
 void D3D12HostDisplay::DestroyRenderSurface()
 {
+  m_window_info.SetSurfaceless();
+
   // For some reason if we don't execute the command list here, the swap chain is in use.. not sure where.
   g_d3d12_context->ExecuteCommandList(true);