Fix recent regression in installation of namelink
The check for whether or not to install a namelink depends on KWSYS_BUILD_SHARED, but this variable wasn't being set until later in CMakeLists.txt, causing the namelink to not be installed if KWSYS_BUILD_SHARED is not explicitly set. Fix this by moving the variable assignment closer to the top of the file.
I have tested and verified this in VTK.