ratelimit: fix off-by-one

The current code might make sense during startup for service restart
limiting:
With burst=1 after starting num is 1, so the next ('first') restart is
still accepted ( 1 <= 1). However, once interval has expired, num is 1
after the first restart, so the second restart is also accepted.

This change is also useful in combination with watchdogs:
With burst=1 and a very large interval the system can be restarted on
the first failure.

src/shared/ratelimit.c

@@ -46,7 +46,7 @@ bool ratelimit_test(RateLimit *r) {
                 goto good;
         }
 
-        if (r->num <= r->burst)
+        if (r->num < r->burst)
                 goto good;
 
         return false;