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

CMakeLists.txt

@@ -47,7 +47,7 @@ set_package_properties(KF5Baloo PROPERTIES DESCRIPTION "File Searching"
 find_package(KF5TextEditor)
 find_package(KWinDBusInterface CONFIG REQUIRED)
 
-find_package(KScreenLocker REQUIRED)
+find_package(KScreenLocker 5.13.80 REQUIRED)
 find_package(ScreenSaverDBusInterface CONFIG REQUIRED)
 find_package(KF5Holidays)
 set_package_properties(KF5Holidays PROPERTIES DESCRIPTION "Holidays provider for Plasma calendar"

ksmserver/CMakeLists.txt

@@ -44,7 +44,7 @@ qt5_add_dbus_interface( ksmserver_KDEINIT_SRCS ${kcminit_xml} kcminit_interface
 set(klauncher_xml ${KINIT_DBUS_INTERFACES_DIR}/kf5_org.kde.KLauncher.xml)
 qt5_add_dbus_interface( ksmserver_KDEINIT_SRCS ${klauncher_xml} klauncher_interface )
 
-qt5_add_dbus_interface( ksmserver_KDEINIT_SRCS ${KDE_INSTALL_FULL_DBUSINTERFACEDIR}/org.kde.screensaver.xml kscreenlocker_interface )
+qt5_add_dbus_interface( ksmserver_KDEINIT_SRCS ${KSCREENLOCKER_DBUS_INTERFACES_DIR}/org.kde.screensaver.xml kscreenlocker_interface )
 
 
 qt5_add_dbus_adaptor( ksmserver_KDEINIT_SRCS org.kde.KSMServerInterface.xml server.h KSMServer )