sim_x11events() polls g_display from the idle loop while the
framebuffer teardown path closes the X connection. Clear the global
Display handle before teardown so the event path stops using it, but
keep the saved local Display pointer for XShmDetach(), XUngrabButton(),
and XCloseDisplay().
This only changes the sim X11 framebuffer shutdown ordering and does
not change user-visible APIs or build configuration.
Signed-off-by: hanzhijian <hanzhijian@zepp.com>
2969c8807e