Upstream: yes https://gitlab.com/Remmina/Remmina/-/merge_requests/2108

commit db8cc0e3bb260c316832d4dfdb308641fcb100af
Author: Alexander Kapshuna <kapsh@kap.sh>
Date:   Sat Aug 22 17:43:29 2020 +0300

    Use previously defined DATADIR to install Kiosk files

diff --git a/data/desktop/CMakeLists.txt b/data/desktop/CMakeLists.txt
index 4f492ce8..eb586af3 100644
--- a/data/desktop/CMakeLists.txt
+++ b/data/desktop/CMakeLists.txt
@@ -154,19 +154,19 @@ if(WITH_KIOSK_SESSION)
     message(STATUS "Kiosk desktop session files will be installed")
     install(
         FILES remmina-gnome-xsession.desktop
-        DESTINATION ${CMAKE_INSTALL_PREFIX}/share/xsessions
+        DESTINATION ${REMMINA_DATADIR}/xsessions
         RENAME remmina-gnome.desktop
         PERMISSIONS OWNER_WRITE OWNER_READ GROUP_READ WORLD_READ
         )
     install(
         FILES remmina-gnome.desktop
-        DESTINATION ${CMAKE_INSTALL_PREFIX}/share/applications
+        DESTINATION ${REMMINA_DATADIR}/applications
         RENAME remmina-gnome.desktop
         PERMISSIONS OWNER_WRITE OWNER_READ GROUP_READ WORLD_READ
         )
     install(
         FILES remmina-gnome.session
-        DESTINATION ${CMAKE_INSTALL_PREFIX}/share/gnome-session/sessions
+        DESTINATION ${REMMINA_DATADIR}/gnome-session/sessions
         RENAME remmina-gnome.session
         PERMISSIONS OWNER_WRITE OWNER_READ GROUP_READ WORLD_READ
         )