PDP11, VAX780, VAX8600, VAX750, VAX730: Fix second DEUNA/DELUA device which would crash the simulator when detaching.  Problem reported by Jordi Guillaumes Pons.
PDP10, PDP11, VAX: Revert effort to Avoid returning "Line Unit" test failed after DMC/DMR master clear if a line is not attached.  To be addressed more thoroughly later.