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/dbus-timer.c

@@ -252,8 +252,7 @@ static int bus_timer_set_transient_property(
 
                         v = new0(TimerValue, 1);
                         if (!v) {
-                                if (c)
-                                        calendar_spec_free(c);
+                                calendar_spec_free(c);
                                 return -ENOMEM;
                         }