Support process.scheduler

Spec: https://github.com/opencontainers/runtime-spec/pull/1188
Fix: https://github.com/opencontainers/runc/issues/3895

Co-authored-by: lifubang <lifubang@acmcoder.com>
Signed-off-by: utam0k <k0ma@utam0k.jp>
Signed-off-by: lifubang <lifubang@acmcoder.com>

libcontainer/setns_init_linux.go

@@ -65,6 +65,12 @@ func (l *linuxSetnsInit) Init() error {
 		unix.Umask(int(*l.config.Config.Umask))
 	}
 
+	if l.config.Config.Scheduler != nil {
+		if err := setupScheduler(l.config.Config); err != nil {
+			return err
+		}
+	}
+
 	if err := selinux.SetExecLabel(l.config.ProcessLabel); err != nil {
 		return err
 	}