Ticket #47623 fix memleak caused by 47347
    
    https://fedorahosted.org/389/ticket/47623
    Reviewed by: tbordaz, nhosoi (Thanks!)
    Branch: 389-ds-base-1.3.2
    Fix Description: Create the mutex if it doesn't exist.
    Platforms tested: RHEL6 x86_64
    Flag Day: no
    Doc impact: no
    (cherry picked from commit 0d4849dd7551347f0e24ac1027f4d0501084dcf3)