daemon unit tests: skip some if non-root

This prevents the following test case failures "go test" is run
as non-root in the daemon/ directory:

> --- FAIL: TestContainerInitDNS (0.02s)
> 	daemon_test.go:209: chown /tmp/docker-container-test-054812199/volumes: operation not permitted
>
> --- FAIL: TestDaemonReloadNetworkDiagnosticPort (0.00s)
>	reload_test.go:525: mkdir /var/lib/docker/network/files/: permission denied
> --- FAIL: TestRootMountCleanup (0.00s)
> 	daemon_linux_test.go:240: assertion failed: error is not nil: operation not permitted

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

daemon/daemon_linux_test.go

@@ -229,6 +229,10 @@ func checkMounted(t *testing.T, p string, expect bool) {
 }
 
 func TestRootMountCleanup(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("root required")
+	}
+
 	t.Parallel()
 
 	testRoot, err := ioutil.TempDir("", t.Name())

daemon/daemon_test.go

@@ -153,6 +153,10 @@ func TestValidContainerNames(t *testing.T) {
 }
 
 func TestContainerInitDNS(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("root required") // for chown
+	}
+
 	tmp, err := ioutil.TempDir("", "docker-container-test-")
 	if err != nil {
 		t.Fatal(err)

daemon/reload_test.go

@@ -1,6 +1,7 @@
 package daemon // import "github.com/docker/docker/daemon"
 
 import (
+	"os"
 	"reflect"
 	"sort"
 	"testing"
@@ -499,6 +500,9 @@ func TestDaemonDiscoveryReloadOnlyClusterAdvertise(t *testing.T) {
 }
 
 func TestDaemonReloadNetworkDiagnosticPort(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("root required")
+	}
 	daemon := &Daemon{
 		imageService: images.NewImageService(images.ImageServiceConfig{}),
 	}