touchpad: cancel taps if we get a timestamp exceeding our interval

If the controller goes to sleep and wakes up during a fast-enough finger
movement, the kernel tracking thinks that the finger ended and a new finger
started elsewhere. The result is that libinput thinks this is a tap-and-drag.

Fix this by simply assuming a tap timeout for anything exceeding our interval
threshold.

Fixes #211

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
17 jobs for wip/touchpad-debounce-timestamps in 24 minutes and 1 second (queued for 36 seconds)
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