COMP: Update DCMTK to fix Syntax warning

This commit fixes a warning occurring when using CMake >= 2.8.12

//--------------
Author: Joerg Riesmeier <dicom@jriesmeier.com>
Date: Wed Jan 21 02:49:54 2015 -0500

Fixed small issue reported by CMake 2.8.12.

A trailing "/" had to be removed in order to keep CMake 2.8.12 quiet.

//--------------

This commit fixes the following warning:

CMake Warning (dev) at CMake/dcmtkPrepare.cmake:317 (INCLUDE):
Syntax Warning in cmake code at

/path/to/Slicer-0-build/DCMTK/CMake/3rdparty.cmake:9:70

Argument not separated from preceding token by whitespace.
Call Stack (most recent call first):
CMakeLists.txt:8 (INCLUDE)
This warning is for project developers. Use -Wno-dev to suppress it.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23897 3bd1e089-480b-0410-8dfb-8563597acbee