Bug 16758 - Caching issues in scripts running in daemon mode

Bug 16758 - Caching issues in scripts running in daemon mode

As L1 cache does not have expiration mechanism, scripts running
in daemon mode (rebuild_zebra.pl -daemon, sip server ?, ...) would
not be aware of any possible changes in the data being cached
in upstream L2 cache.

This patch adds ->flush_L1_caches() call in rebuild_zebra.pl
inside daemon mode loop.

To test:

1) apply patch
2) ensure that rebuild_zebra.pl -daemon is still working properly,
without any noticeable performance degradation
3) stop memcached daemon and try to run rebuild_zebra.pl -daemon
again: there should be a warning emitted stating that the script
is running in daemon mode but without recommended caching system

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>