util: Do not leak @handles in stop netlink event service

Commit e3ba4025 introduced srv->handles and VIR_RESIZE_N to allocate
@handles as necessary, but did not free the handles during when calling
virNetlinkEventServiceStop.

src/util/virnetlink.c

@@ -758,6 +758,7 @@ virNetlinkEventServiceStop(unsigned int protocol)
     }
 
     server[protocol] = NULL;
+    VIR_FREE(srv->handles);
     virNetlinkEventServerUnlock(srv);
 
     virMutexDestroy(&srv->lock);