Should be fixed, since CMake 3.2 is the most current version which users will download.
This is the CMake output after "make VTK" on superbuild level:
CMake Error at Utilities/KWSys/vtksys/CMakeLists.txt:1004 (ADD_LIBRARY):
CXX_STANDARD is set to invalid value ''
CMake Error at CMake/vtkModuleMacros.cmake:448 (add_library):
CXX_STANDARD is set to invalid value ''
Call Stack (most recent call first):
CMake/vtkModuleMacros.cmake:532 (vtk_add_library) Common/Core/CMakeLists.txt:594 (vtk_module_library)