Let the Renderer decide when to exit fullscreen.

This ensures the transition from/to exclusive mode happens while the RenderFrame is fullscreen.

This prevents fullscreen loops and relieves us of having to restore the window size after we exit fullscreen.

Source/Core/DolphinWX/MainAndroid.cpp

@@ -94,6 +94,9 @@ void Host_GetRenderWindowSize(int& x, int& y, int& width, int& height)
 }
 
 void Host_RequestRenderWindowSize(int width, int height) {}
+
+void Host_RequestFullscreen(bool fullscreen) {}
+
 void Host_SetStartupDebuggingParameters()
 {
 }