libev-4.22 C++ does not build without EV_SIGNAL_ENABLE

[Arūnas Česonis]

diff --git a/ev++.h b/ev++.h
index 4f0a36a..d1c84c8 100644
--- a/ev++.h
+++ b/ev++.h
@@ -337,10 +337,12 @@ namespace ev {
       ev_feed_fd_event (EV_AX_ fd, revents);
     }

+#if EV_SIGNAL_ENABLE
     void feed_signal_event (int signum) throw ()
     {
       ev_feed_signal_event (EV_AX_ signum);
     }
+#endif

 #if EV_MULTIPLICITY
     struct ev_loop* EV_AX;