Split Linux platform target and move runtime/platform state

src/app.h

@@ -155,16 +155,6 @@ public:
     int idle_ms = 100;
     pp::platform::PlatformServices* platform_services_ = nullptr;
     
-#if defined(__IOS__) && defined(__OBJC__)
-    GameViewController* ios_view;
-    AppDelegate* ios_app;
-#elif defined(__OSX__) && defined(__OBJC__)
-    View* osx_view;
-    AppOSX* osx_app;
-#elif __LINUX__ || __WEB__
-    GLFWwindow* glfw_window;
-#endif
-
 #ifdef __ANDROID__
     struct android_app* and_app;
     struct engine* and_engine;