HostDisplay: Implement exclusive fullscreen for D3D11 renderer

src/core/host_display.h

@@ -66,6 +66,8 @@ public:
   virtual void DestroyRenderDevice() = 0;
   virtual void DestroyRenderSurface() = 0;
   virtual bool ChangeRenderWindow(const WindowInfo& wi) = 0;
+  virtual bool IsFullscreen() = 0;
+  virtual bool SetFullscreen(bool fullscreen, u32 width, u32 height, float refresh_rate) = 0;
   virtual bool CreateResources() = 0;
   virtual void DestroyResources() = 0;
 

src/core/settings.cpp

@@ -5,6 +5,7 @@
 #include "host_interface.h"
 #include <algorithm>
 #include <array>
+#include <cctype>
 #include <numeric>
 
 Settings g_settings;