Bug #944: Deletion of unnecessary checks before a few calls of systemd functions

The following functions return immediately if a null pointer was passed.
* calendar_spec_free
* link_address_free
* manager_free
* sd_bus_unref
* sd_journal_close
* udev_monitor_unref
* udev_unref

It is therefore not needed that a function caller repeats a corresponding check.

This issue was fixed by using the software Coccinelle 1.0.1.

src/core/timer.c

@@ -56,10 +56,7 @@ void timer_free_values(Timer *t) {
 
         while ((v = t->values)) {
                 LIST_REMOVE(value, t->values, v);
-
-                if (v->calendar_spec)
-                        calendar_spec_free(v->calendar_spec);
-
+                calendar_spec_free(v->calendar_spec);
                 free(v);
         }
 }