pkg/osutil: add FreeBSD CPU usage.

Change-Id: Ic2cf8f8e422d2aef8c7c5e217da988d14735a416

pkg/osutil/cpu_freebsd.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2014 The Camlistore 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 osutil
+
+import (
+	"syscall"
+	"time"
+)
+
+func init() {
+	cpuUsage = cpuFreeBSD
+}
+
+func cpuFreeBSD() time.Duration {
+	var ru syscall.Rusage
+	syscall.Getrusage(0, &ru)
+	return time.Duration(ru.Utime.Nano())
+}