NAME
        UnLock -- Unlock a directory or file

    SYNOPSIS
        UnLock( lock )
                D1

        void UnLock(BPTR)

    FUNCTION
        The filing system lock (obtained from lock(), duplock(), or
        createdir()) is removed and deallocated.

    INPUTS
        lock - BCPL pointer to a lock

    NOTE
        passing zero to UnLock() is harmless

    SEE ALSO
        lock(), duplock(), parentoffh(), duplockfromfh()