Follow up from #1611.
We want to be able to continue to use uinput when upgrading a server.
The patch attached almost kinda works, with some problems:
- requires "xprop" to find the device uuid... ugly
- the part of the patch that uses the device name to match the device cannot be used, as udev doesn't understand regex in the ATTRS match section... so we'll need to use something else (the device part of the USBID?)
- we chmod the device to 0666 initially so that the existing X11 server can add the new device, that's dangerous - we need to chmod / chown it to the user the server belongs to