Bug 659456 - Incorrect usage of ber_printf() in winsync code
    
    In the winsync code, we can end up passing a NULL pointer to
    ber_printf() when we want to add an octet string for the dirsync
    cookie.  This causes a SIGABRT when using a debug build on F14
    since you are not supposed to pass a NULL.
    
    The fix is to pass an empty string when the cookie is NULL.