Report joystick added/removed events even if we don't have udev.

T. Joseph Carter

As discussed (possibly to death), the Linux joystick driver does not actually report events for added or removed joysticks when you haven't got udev support.

We simply cannot know about removed joysticks without udev.  But we can (and we should) report adding them.  This brings the legacy case in line with pretty much the rest of SDL's joystick drivers.