lxc-unprivileged: fix mount options issue

Fix an issue that cause unprivileged containers to not boot if /proc and
/sys are mounted with the `noatime` option.

At boot time /proc and /sys are remounted with the `relatime` option
using a dedicated init.d script.

utils/lxc/Makefile

@@ -97,8 +97,9 @@ define Package/lxc-unprivileged/description
 endef
 
 define Package/lxc-unprivileged/install
-	$(INSTALL_DIR) $(1)/etc/uci-defaults
+	$(INSTALL_DIR) $(1)/etc/uci-defaults $(1)/etc/init.d
 	$(INSTALL_DATA) ./files/lxc-unprivileged.defaults $(1)/etc/uci-defaults/lxc-unprivileged
+	$(INSTALL_BIN) ./files/lxc-unprivileged.init $(1)/etc/init.d
 endef
 
 define Package/lxc/config

utils/lxc/files/lxc-unprivileged.init

@@ -0,0 +1,13 @@
+#!/bin/sh /etc/rc.common
+
+. /lib/functions.sh
+
+START=98
+
+# Remount /proc and /sys on host with relatime option,
+# required for unprivileged containers to boot correctly.
+boot() {
+	mount -t proc -o remount,rw,nosuid,nodev,noexec,relatime proc /proc
+	mount -t sysfs -o remount,rw,nosuid,nodev,noexec,relatime sysfs /sys
+}
+