Add internal function for telegraf version (#4828)

cmd/telegraf/telegraf.go

@@ -326,6 +326,16 @@ func main() {
 		return
 	}
 
+	shortVersion := version
+	if shortVersion == "" {
+		shortVersion = "unknown"
+	}
+
+	// Configure version
+	if err := internal.SetVersion(shortVersion); err != nil {
+		log.Println("Telegraf version already configured to: " + internal.Version())
+	}
+
 	if runtime.GOOS == "windows" && !(*fRunAsConsole) {
 		svcConfig := &service.Config{
 			Name:        *fServiceName,