test: fix check for pause on cgroup v2

There is no freezer controller in the cgroup root, use the current
cgroup to look it up.

The test was never running on cgroup v2.

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

test/e2e/pause_test.go

@@ -2,7 +2,9 @@ package integration
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/containers/libpod/pkg/cgroups"
@@ -32,7 +34,13 @@ var _ = Describe("Podman pause", func() {
 		Expect(err).To(BeNil())
 
 		if cgroupsv2 {
-			_, err := os.Stat("/sys/fs/cgroup/cgroup.freeze")
+			b, err := ioutil.ReadFile("/proc/self/cgroup")
+			if err != nil {
+				Skip("cannot read self cgroup")
+			}
+
+			path := filepath.Join("/sys/fs/cgroup", strings.TrimSuffix(strings.Replace(string(b), "0::", "", 1), "\n"), "cgroup.freeze")
+			_, err = os.Stat(path)
 			if err != nil {
 				Skip("freezer controller not available on the current kernel")
 			}