gluon-autoupdater: add locking to ensure no two instances of the autoupdater run in parallel

package/gluon-autoupdater/files/lib/gluon/autoupdater/autoupdate

+#!/bin/sh
+
+lock /var/gluon/autoupdater.lock
+autoupdater "$@"
+lock -u /var/gluon/autoupdater.lock

package/gluon-autoupdater/files/lib/gluon/upgrade/autoupdater/invariant/010-autoupdater

@@ -49,5 +49,5 @@ autoupdater_util.randomseed()
 
 -- Perform updates at a random time between 04:00 and 05:00
 local f = io.open('/lib/gluon/cron/autoupdater', 'w')
-f:write(string.format('%i 4 * * * /usr/sbin/autoupdater\n', math.random(0, 59)))
+f:write(string.format('%i 4 * * * /lib/gluon/autoupdater/autoupdate\n', math.random(0, 59)))
 f:close()