Update tde_setup_dbus macro

+ Old versions of dbus do not include a definition for system_bus_services_dir.
+ The value for system_bus_services_dir is derived from session_bus_services_dir.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit d02522eda1)

modules/TDEMacros.cmake

@@ -1905,24 +1905,32 @@ macro( tde_setup_dbus )
     endif( )
   endif( )
 
-  if( NOT DEFINED DBUS_SERVICE_DIRECTORY )
+  if( NOT DEFINED DBUS_SESSION_DIRECTORY )
     execute_process(
       COMMAND ${PKG_CONFIG_EXECUTABLE}
-        dbus-1 --variable=system_bus_services_dir
-      OUTPUT_VARIABLE DBUS_SERVICE_DIRECTORY
+        dbus-1 --variable=session_bus_services_dir
+      OUTPUT_VARIABLE DBUS_SESSION_DIRECTORY
       OUTPUT_STRIP_TRAILING_WHITESPACE
     )
-    message( STATUS "Using " ${DBUS_SERVICE_DIRECTORY} " for DBUS system service files" )
+    message( STATUS "Using " ${DBUS_SESSION_DIRECTORY} " for DBUS session service files" )
   endif( )
 
-  if( NOT DEFINED DBUS_SESSION_DIRECTORY )
+  if( NOT DEFINED DBUS_SERVICE_DIRECTORY )
     execute_process(
       COMMAND ${PKG_CONFIG_EXECUTABLE}
-        dbus-1 --variable=session_bus_services_dir
-      OUTPUT_VARIABLE DBUS_SESSION_DIRECTORY
+        dbus-1 --variable=system_bus_services_dir
+      OUTPUT_VARIABLE DBUS_SERVICE_DIRECTORY
       OUTPUT_STRIP_TRAILING_WHITESPACE
     )
-    message( STATUS "Using " ${DBUS_SESSION_DIRECTORY} " for DBUS session service files" )
+    if( "${DBUS_SERVICE_DIRECTORY}" STREQUAL "" )
+      if( "${DBUS_SESSION_DIRECTORY}" MATCHES "/services$" )
+        string( REGEX REPLACE "/services$" "/system-services"
+                DBUS_SERVICE_DIRECTORY "${DBUS_SESSION_DIRECTORY}" )
+      else( )
+        tde_message_fatal( "Directory for DBUS system service files can not be determined." )
+      endif( )
+    endif( )
+    message( STATUS "Using " ${DBUS_SERVICE_DIRECTORY} " for DBUS system service files" )
   endif( )
 
   if( NOT "${ARGV}" STREQUAL "" AND NOT DBUS_TQT_FOUND )