VOL-2017 voltha-lib moved from voltha-go;
release version 2.2.1

Based on voltha-go commit 5259f8e52b3e3f5c7ad422a4b0e506e1d07f6b36

Change-Id: I8bbecdf456e420714a4016120eafc0d237c80565
diff --git a/vendor/github.com/armon/go-metrics/const_unix.go b/vendor/github.com/armon/go-metrics/const_unix.go
new file mode 100644
index 0000000..31098dd
--- /dev/null
+++ b/vendor/github.com/armon/go-metrics/const_unix.go
@@ -0,0 +1,12 @@
+// +build !windows
+
+package metrics
+
+import (
+	"syscall"
+)
+
+const (
+	// DefaultSignal is used with DefaultInmemSignal
+	DefaultSignal = syscall.SIGUSR1
+)