Bruce's fix for when dk_ndrive >= DK_NDRIVE.  Fixes CDROM changer and other "lots of CDROM devices" problems.  This code should be put in a single place.
Bruce's fix for when dk_ndrive >= DK_NDRIVE.  Fixes CDROM changer
and other "lots of CDROM devices" problems.  This code should be
put in a single place.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase