NAME
    DupLock -- Duplicate a lock
SYNOPSIS
    lock = DupLock( lock )
    D0              D1
    BPTR DupLock(BPTR)
FUNCTION
    DupLock() is passed a shared filing system lock.  This is the ONLY
    way to obtain a duplicate of a lock... simply copying is not
    allowed.
    Another lock to the same object is then returned.  It is not
    possible to create a copy of a exclusive lock.
    A zero return indicates failure.
INPUTS
    lock - BCPL pointer to a lock
RESULTS
    newLock - BCPL pointer to a lock
SEE ALSO
    lock(), unlock(), duplockfromfh(), parentoffh()