check return value of syscall.Chdir when changing working directory

AUTHORS

@@ -185,4 +185,5 @@ Vladimir Kirillov <proger@wilab.org.ua>
 Walter Stanish <walter@pratyeka.org>
 Wes Morgan <cap10morgan@gmail.com>
 Will Dietz <w@wdtz.org>
+Yang Bai <hamo.by@gmail.com>
 Zaiste! <oh@zaiste.net>

sysinit.go

@@ -27,7 +27,9 @@ func setupWorkingDirectory(workdir string) {
 	if workdir == "" {
 		return
 	}
-	syscall.Chdir(workdir)
+	if err := syscall.Chdir(workdir); err != nil {
+		log.Fatalf("Unable to change dir to %v: %v", workdir, err)
+	}
 }
 
 // Takes care of dropping privileges to the desired user