Ticket #48289 - 389-ds-base: ldclt-bin killed by SIGSEGV
Description: If NULL source string was passed to parseFilter, it caused
NULL dereference.
https://fedorahosted.org/389/ticket/48289
Reviewed by nhosoi@redhat.com.
(cherry picked from commit 5b33c781d2568c930a0856f0a42c1e1d53e3358f)