Whether a device is a trackball or not is a physical property so we should
store this globally, in one place. The new property must be set in addition to
ID_INPUT_MOUSE, otherwise existing clients won't detect the device.
No actual code changes required, the default match rule is simply checking for
"Trackball" in the name (in a few versions), other entries need to be added
manually.
Peter Hutterer
d5c3b228f0