Fix of threa private initialization
        The initialization of the thread private variable was buggy.
        The private variable required an allocated struct (per thread).
        The struct is allocated on demand (during get/set) when the
        retrieved (PR_GetThreadPrivate) struct is NULL.
        Improve debug messages
        A pstack is showing threadId that differs from the
        the thread pointer. To match logs with pstack
        better to display the threadId
        Ignores updates under cn=config/cn=schema
       The true cause of the hang was that some updates on 'cn=config'
        can skip the BEPOST phase. (in this bug it was the maxbersize setting).
        The consequence is that the slapi-nis map lock was acquired but not released.
        The fix consist to ignore (not lock slapi-nis map) write operation done
        on 'cn=config' and 'cn=schema'