Fix autotests on FreeBSD

Summary:
01:27:20 /usr/home/jenkins/workspace/Extragear wacomtablet kf5-qt5 FreeBSDQt5.10/autotests/faketablet/faketablet.cpp:27:10: fatal error: 'linux/input.h' file not found
01:27:20 #include <linux/input.h>
01:27:20 ^~~~~~~~~~~~~~~

Reviewers: valeriymalov

Reviewed By: valeriymalov

Subscribers: valeriymalov

Differential Revision: https://phabricator.kde.org/D12705