Avoid CStoreEditor failures on missing log-protect

When the log_protect configuration chunk is not present in
opensrf_core.xml, gracefully move on without it.  This prevents errors
like:

Can't call method \"shared\" on an undefined value at
/usr/local/share/perl/5.10.1/OpenILS/Utils/CStoreEditor.pm line 646.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Mike Rylander <mrylander@gmail.com>