COMP: Fix pathing bug in packaging

For the preferred directory for DCMTK install packages and
DCMT_DIR are not consistent.  THis patch passes the correct pathing
to the bin directory needed for packaging.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21842 3bd1e089-480b-0410-8dfb-8563597acbee