Update systemstat9 to allow compilation on OSX

The latest version of system statadds stubbed out methods for non-Linux OSes:
https://bitbucket.org/bertimus9/systemstat/pull-requests/2

vendor/bitbucket.org/bertimus9/systemstat/systemstat_ex.go

@@ -0,0 +1,49 @@
+// Copyright (c) 2013 Phillip Bond
+// Licensed under the MIT License
+// see file LICENSE
+
+// +build !linux
+
+package systemstat
+
+import (
+	"syscall"
+	"time"
+)
+
+func getUptime(procfile string) (uptime UptimeSample) {
+	notImplemented("getUptime")
+	uptime.Time = time.Now()
+	return
+}
+
+func getLoadAvgSample(procfile string) (samp LoadAvgSample) {
+	notImplemented("getLoadAvgSample")
+	samp.Time = time.Now()
+	return
+}
+
+func getMemSample(procfile string) (samp MemSample) {
+	notImplemented("getMemSample")
+	samp.Time = time.Now()
+	return
+}
+
+func getProcCPUSample() (s ProcCPUSample) {
+	var processInfo syscall.Rusage
+	syscall.Getrusage(syscall.RUSAGE_SELF, &processInfo)
+
+	s.Time = time.Now()
+	s.ProcMemUsedK = int64(processInfo.Maxrss)
+	s.User = float64(processInfo.Utime.Usec)/1000000 + float64(processInfo.Utime.Sec)
+	s.System = float64(processInfo.Stime.Usec)/1000000 + float64(processInfo.Stime.Sec)
+	s.Total = s.User + s.System
+
+	return
+}
+
+func getCPUSample(procfile string) (samp CPUSample) {
+	notImplemented("getCPUSample")
+	samp.Time = time.Now()
+	return
+}