Fixed setting the window visibility on iOS and Android

src/video/android/SDL_androidwindow.c

@@ -44,6 +44,7 @@ Android_CreateWindow(_THIS, SDL_Window * window)
 
     window->flags &= ~SDL_WINDOW_RESIZABLE;     /* window is NEVER resizeable */
     window->flags |= SDL_WINDOW_FULLSCREEN;     /* window is always fullscreen */
+    window->flags &= ~SDL_WINDOW_HIDDEN;
     window->flags |= SDL_WINDOW_SHOWN;          /* only one window on Android */
     window->flags |= SDL_WINDOW_INPUT_FOCUS;    /* always has input focus */    
 

src/video/uikit/SDL_uikitwindow.m

@@ -88,7 +88,9 @@ static int SetupWindowData(_THIS, SDL_Window *window, UIWindow *uiwindow, SDL_bo
 
     window->driverdata = data;
 
-    window->flags |= SDL_WINDOW_SHOWN;            /* only one window on iOS, always shown */
+    /* only one window on iOS, always shown */
+    window->flags &= ~SDL_WINDOW_HIDDEN;
+    window->flags |= SDL_WINDOW_SHOWN;
 
     // SDL_WINDOW_BORDERLESS controls whether status bar is hidden.
     // This is only set if the window is on the main screen. Other screens