fix tasklist structure

When calling fb tasks form c code it is possible to create loops, which cause the server to crash. To avoid this, execution should be triggered by the tasklist association. In places where this is not possible (due to limitations of the concept) it is imperative to check that no loops exist. One possibility is to traverse up the tasklist and look for the UrTask.

This merge request fixes these issues for the fb and ssc library.

syslibs/fb/include/fb_database.h

@@ -4,7 +4,7 @@
 ***   #####################################                                 ***
 ***                                                                         ***
 ***   L T S o f t                                                           ***
-***   Agentur fr Leittechnik Software GmbH                                 ***
+***   Agentur für Leittechnik Software GmbH                                 ***
 ***   Brabanterstr. 13                                                      ***
 ***   D-50171 Kerpen                                                        ***
 ***   Tel : 02237/92869-2                                                   ***
@@ -94,6 +94,13 @@ OV_DLLFNCEXPORT OV_RESULT fb_database_checkstruct(void);
 */
 OV_DLLFNCEXPORT void* fb_database_geturtask(void);
 
+/*
+ * check if task is connected to UrTask or an initial task
+ */
+OV_DLLFNCEXPORT OV_BOOL fb_task_has_initial_taskparent(
+	OV_INSTPTR_fb_task ptask
+);
+
 /*
 *	Get libraries container object
 */