sd-event: drop _likely_()

This is not certain to be likely.

Lennart says: a frequent usecase is invoking some function regularly in intervals
in such a case every single iteration we'll have to rearm

src/libsystemd/sd-event/sd-event.c

@@ -1755,7 +1755,7 @@ static int event_arm_timer(
         assert(e);
         assert(d);
 
-        if (_likely_(!d->needs_rearm))
+        if (!d->needs_rearm)
                 return 0;
         else
                 d->needs_rearm = false;