The majority of Clutter input events require a time so that that the
upper levels of abstraction can identify the ordering of events and also
work out a click count.
Although some Wayland events have microsecond timestamps not all those
that Clutter expects do have. Therefore we would need to create some
fake times for those events. Instead we always calculate our own time
using the monotonic time.
https://bugzilla.gnome.org/show_bug.cgi?id=697285
7df59887d7