This was required when we started supporting hotplugging to avoid duplicate
events. These days the drawback of not being able to record events in the case
of a bug is significant.

Check the configuration source on init. If the device was hotplugged through a
a server config backend, disable the grab. If the device was statically
configured through an xorg.conf then leave the default grab enabled to avoid
a duplicate device.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>