Specify minimum version for KScreenlocker, use correct DBUS path
Summary:
org.kde.screensaver.xml is only part of KScreenlocker starting with
version 5.13.80, also the installation directory is not exported in
earlier versions.
Depends on D15228
Test Plan:
Try to build with kscreenlocker 5.13.0
Try to build with kscreenlocker 5.13.80
Reviewers: Plasma, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D15229