BUG: Add rpath to DCMTK application when building MacOSX package. Fixes #3827

While commit addresses issue #3827, the problem applies for the other
executable bundled in the ./Slicer.app/Contents/bin directory. A more
general solution would have to be implemented to also fix these. This
is captured by issue #3831

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23666 3bd1e089-480b-0410-8dfb-8563597acbee