fix: "smbstatus check fails on new systems"

For newer versions of smbstatus (Version 3.6.6) smbstatus will report
"/var/run/samba/locking.tdb not initialised" instead of "sessionid.tdb not
initialised". This commit enables the additional check for the "locking.tdb"
to enable autoshutdown again if Samba is not activated.
Merge pull request #4 from christianrauch/master

fix: "smbstatus check fails on new systems"