BUG: Remove unused manual variables from superbuild of ImageViewer
BUG: Remove unused manual variables from superbuild of ImageViewer

Fixes the CMake Warning that manually-specified variables (CMAKE_EXE_LINKER_FLAGS, CMAKE_SHARED_LINKER_FLAGS) were not used by the project.

Change-Id: If471d9fb242227464462df1a54456fe3da22735d

aylward/ITKTubeTK,KitwareMedical/ITKTubeTK,aylward/ITKTubeTK,sumedhasingla/TubeTK,cdeepakroy/TubeTK,KitwareMedical/TubeTK,sumedhasingla/TubeTK,aylward/ITKTubeTK,sumedhasingla/TubeTK,aylward/ITKTubeTK,cdeepakroy/TubeTK,LucasGandel/TubeTK,KitwareMedical/TubeTK,LucasGandel/TubeTK,KitwareMedical/ITKTubeTK,KitwareMedical/ITKTubeTK,KitwareMedical/ITKTubeTK,thewtex/TubeTK,thewtex/TubeTK,matthieuheitz/TubeTK,cdeepakroy/TubeTK,cdeepakroy/TubeTK,KitwareMedical/TubeTK,matthieuheitz/TubeTK,thewtex/TubeTK,LucasGandel/TubeTK,matthieuheitz/TubeTK,thewtex/TubeTK,matthieuheitz/TubeTK,KitwareMedical/TubeTK,LucasGandel/TubeTK,sumedhasingla/TubeTK