veyron/lib/signals: Remove dependence on rt.R()

Change-Id: I451318d807336a157ee3b92cb85921f7f2ce02c4
diff --git a/tools/debug/impl.go b/tools/debug/impl.go
index e36d950..9c5effc 100644
--- a/tools/debug/impl.go
+++ b/tools/debug/impl.go
@@ -554,7 +554,7 @@
 	fmt.Fprintln(cmd.Stdout())
 	fmt.Fprintln(cmd.Stdout(), "Hit CTRL-C to exit")
 
-	<-signals.ShutdownOnSignals()
+	<-signals.ShutdownOnSignals(runtime)
 	return nil
 }