Win32: fix non closing window when clicking the X

it wasn't getting out of the event polling loop

src/win32screen.c

@@ -161,6 +161,7 @@ static LRESULT CALLBACK Win32_WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LP
     break;
   case WM_CLOSE:
     Quit_is_required = 1;
+    user_feedback_required = 1;
     return 0;
   case WM_ERASEBKGND:
     // the background should be erased