Increase default memory limit for cli scripts to prevent runtime memory issues

[rprofijt]

The default cli memory limit of php in Debian/Ubuntu is -1, in include/cli_check.php however, the limit is overwritten (to 500MB) which causes our cli scripts (poller_reindex) to fail.

[TheWitness]

Unlimited makes sense to me. The reindex can take a lot of memory.

[TheWitness]

@rprofijt, thanks for reporting. I've opened the flood gates. I think it'll be fine though. Not many systems have less than a dozen or so GB these days.