touchpad: Fix for #339, multi-finger clickpad drag

Allowing gestures when holding a physical click enables tasks like
switching workspaces while dragging an icon, but this should only be
possible with a *thumb* holding down the clickpad, not fingers. This
commit restores the ability to hold down the clickpad with two or three
fingers to right- or middle-drag.
23 jobs for multi-finger-clickpad-drag in 8 minutes and 20 seconds (queued for 37 seconds)
latest
Status Job ID Name Coverage
  Container Prep
passed #504728
arch:rolling@container-prep

00:01:13

passed #504725
fedora:29@container-prep

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passed #504724
fedora:30@container-prep

00:00:54

passed #504729
freebsd:11.2@container-prep

00:01:13

passed #504726
ubuntu:18.10@container-prep

00:01:03

passed #504727
ubuntu:19.04@container-prep

00:01:03

 
  Build
passed #504745
arch:rolling@default-build

00:01:20

passed #504730
fedora:29@default-build

00:01:21

passed #504738
fedora:30@build-no-debuggui

00:01:19

passed #504739
fedora:30@build-no-debuggui-nodeps

00:01:42

passed #504736
fedora:30@build-no-docs

00:01:49

passed #504737
fedora:30@build-no-docs-nodeps

00:01:09

passed #504734
fedora:30@build-no-libwacom

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passed #504735
fedora:30@build-no-libwacom-nodeps

00:01:29

passed #504740
fedora:30@build-no-tests

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passed #504741
fedora:30@build-no-tests-nodeps

00:01:28

passed #504731
fedora:30@default-build

00:01:23

passed #504732
fedora:30@default-build-release

00:00:32

passed #504733
fedora:30@scan-build

00:02:36

passed #504742
fedora:30@valgrind

00:01:36

passed #504746
freebsd:11.2@default-build

00:00:21

passed #504743
ubuntu:18.10@default-build

00:01:16

passed #504744
ubuntu:19.04@default-build

00:01:16