libct/cg/fs2: fix GetStats for unsupported hugetlb

In case hugetlb is not supported, GetStats() should not error out,
and yet it does.

Assume that if GetHugePageSize return an error, hugetlb is
not supported (this is what cgroup v1 manager do).

Fixes: 89a87adb
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit 916c6a1539)
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

libcontainer/cgroups/fs2/hugetlb.go

@@ -30,10 +30,7 @@ func setHugeTlb(dirPath string, r *configs.Resources) error {
 }
 
 func statHugeTlb(dirPath string, stats *cgroups.Stats) error {
-	hugePageSizes, err := cgroups.GetHugePageSize()
-	if err != nil {
-		return errors.Wrap(err, "failed to fetch hugetlb info")
-	}
+	hugePageSizes, _ := cgroups.GetHugePageSize()
 	hugetlbStats := cgroups.HugetlbStats{}
 
 	for _, pagesize := range hugePageSizes {