Change: having USERDN and SELFDN using the same DS_LASUserDnAttrEval routine

fix: https://fedorahosted.org/389/attachment/ticket/47653/0006-Ticket-47653-Need-a-way-to-allow-users-to-create-ent.patch
test case: https://fedorahosted.org/389/attachment/ticket/47653/0001-Ticket-47653-test-case.patch