The following sequence currently generates a right-button event:
	finger 1 down
	finger 2 down
	finger 1 up
	finger 2 held down

This is easily triggered with short scroll events. There are two issues here:
first is that the tapping code elsewhere treats any tap with a second finger
down as a left-button tap, not a right button one. So if anything, we should
generate a left button click here, not a right button click.

Arguably, generating a button click here is wrong though, it's not a very well
defined sequence and relatively difficult to trigger intentionally. So the
best solution here is to simply ignore the release event and move straight
back to state HOLD - unless the second finger is released within the timeout.
If the finger is set down again during the timeout, we move straight to
TOUCH_2_HOLD - this could eventually be interpreted as a tap, but not for now.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
(cherry picked from commit 79570fd4)