cri: implement RuntimeConfig rpc

The rpc only reports one field, i.e. the cgroup driver, to kubelet.
Containerd determines the effective cgroup driver by looking at all
runtime handlers, starting from the default runtime handler (the rest in
alphabetical order), and returning the cgroup driver setting of the
first runtime handler that supports one. If no runtime handler supports
cgroup driver (i.e. has a config option for it) containerd falls back to
auto-detection, returning systemd if systemd is running and cgroupfs
otherwise.

This patch implements the CRI server side of Kubernetes KEP-4033:
https://github.com/kubernetes/enhancements/tree/master/keps/sig-node/4033-group-driver-detection-over-cri

Signed-off-by: Markus Lehtonen <markus.lehtonen@intel.com>

vendor/github.com/opencontainers/runc/libcontainer/cgroups/fs2/hugetlb.go

@@ -0,0 +1,48 @@
+package fs2
+
+import (
+	"strconv"
+
+	"github.com/opencontainers/runc/libcontainer/cgroups"
+	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
+	"github.com/opencontainers/runc/libcontainer/configs"
+)
+
+func isHugeTlbSet(r *configs.Resources) bool {
+	return len(r.HugetlbLimit) > 0
+}
+
+func setHugeTlb(dirPath string, r *configs.Resources) error {
+	if !isHugeTlbSet(r) {
+		return nil
+	}
+	for _, hugetlb := range r.HugetlbLimit {
+		if err := cgroups.WriteFile(dirPath, "hugetlb."+hugetlb.Pagesize+".max", strconv.FormatUint(hugetlb.Limit, 10)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func statHugeTlb(dirPath string, stats *cgroups.Stats) error {
+	hugetlbStats := cgroups.HugetlbStats{}
+	for _, pagesize := range cgroups.HugePageSizes() {
+		value, err := fscommon.GetCgroupParamUint(dirPath, "hugetlb."+pagesize+".current")
+		if err != nil {
+			return err
+		}
+		hugetlbStats.Usage = value
+
+		fileName := "hugetlb." + pagesize + ".events"
+		value, err = fscommon.GetValueByKey(dirPath, fileName, "max")
+		if err != nil {
+			return err
+		}
+		hugetlbStats.Failcnt = value
+
+		stats.HugetlbStats[pagesize] = hugetlbStats
+	}
+
+	return nil
+}