NAME
   GiveUnit - Free the disk back up
SYNOPSIS
   GiveUnit(), DRResource
                A6
    void GiveUnit();
FUNCTION
    This routine frees the disk after a driver is done with it.
    If others are waiting, it will notify them.
INPUTS
RESULTS
EXCEPTIONS
SEE ALSO
    getunit
BUGS
    In pre-V36, GiveUnit didn't check if you owned the unit.  A patch
    for this was part of 1.3.1 SetPatch.  Fixed in V36.