Full restructure in accordance with

- pkg/{subsystem}/{package} style
  - modify Makefile to reflect the new style,
    consolidate various entries
  - add a dummy ``main.go`` at top level

pkg/os/sysctl/sysctl_test.go

@@ -0,0 +1,22 @@
+// !build linux,amd64
+
+package sysctl
+
+import (
+	"testing"
+
+	. "gopkg.in/check.v1"
+)
+
+type MySuite struct{}
+
+var _ = Suite(&MySuite{})
+
+func Test(t *testing.T) { TestingT(t) }
+
+func (s *MySuite) TestSysctl(c *C) {
+	sysctl := Sysctl{}
+	err := sysctl.Get()
+	c.Assert(err, IsNil)
+	c.Assert(sysctl.Sysattrmap, Not(Equals), 0)
+}