wsi/x11: xcb_wait_for_special_event failure is an error
The only ways that function can return NULL are:
- the xcb connection was closed
- the window for the swapchain was destroyed
- the special event listener was unregistered from another thread
- malloc failure
All of these are permanent errors, the swapchain is no longer in a usable state, so we should treat this as VK_ERROR_SURFACE_LOST_KHR.