Make sure our pixel size is up to date at window creation

This guarantees that the application will always get SDL_EVENT_WINDOW_PIXEL_SIZE_CHANGED when a window is created.

Fixes https://github.com/libsdl-org/SDL/issues/7441

src/video/SDL_video.c

@@ -1860,6 +1860,9 @@ SDL_Window *SDL_CreateWindow(const char *title, int w, int h, Uint32 flags)
         SDL_UpdateFullscreenMode(window, SDL_TRUE);
     }
 
+    /* Make sure window pixel size is up to date */
+    SDL_CheckWindowPixelSizeChanged(window);
+
     return window;
 }