cronjobs erroneously report removed lock files

[Hartmut Holzgraefe]

When starting the mail queue and download cronjobs with --fix-locks they will always print that they removed lock files even when no lock file existed at all.

When running this within a cron job an email report will always be triggered, i'd rather like to have a report sent to me only if there really was a stale lock file that needed to be removed.

[Hartmut Holzgraefe (hartmut-php)]

Branch fixes this by making Lock::release() return true if it actually removed a lock file, false otherwise and only printing "removed lock file" messages in the cron job scripts if true is returend from Lock::release()

[Harri Porten (porten-deactivatedaccount)]

The nasty part about the code (not necessarily the patch itself) is that 'false' will be returned from release() in cases of both file missing *and* the release failing.

Maybe it would be easiest to reverse the logic? "Failed to remove lock file" is printed out if the operation fails but *no* output is printed in the two other cases.

[Elan Ruusamäe (glen666)]

Committed revision 4453.