Fix darwin build (volcano-sh#1)

pkg/signals/signal_darwin.go

@@ -0,0 +1,27 @@
+//go:build darwin
+// +build darwin
+
+/*
+Copyright 2021 The Volcano Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package signals
+
+import (
+	"os"
+	"syscall"
+)
+
+var shutdownSignals = []os.Signal{os.Interrupt, syscall.SIGTERM}