ExternalProject_Add_Step requires COMMAND parameter with VisualStudioi. See #32

A bug has been reported on CMake bug tracker
See http://public.kitware.com/Bug/view.php?id=12430

SuperBuild.cmake

@@ -282,6 +282,8 @@ IF(NOT DEFINED SUPERBUILD_EXCLUDE_CTKBUILD_TARGET OR NOT SUPERBUILD_EXCLUDE_CTKB
   # This custom external project step forces the build and later
   # steps to run whenever a top level build is done...
   ExternalProject_Add_Step(${proj} forcebuild
+    COMMAND ${CMAKE_COMMAND} -E echo_append ""
+    COMMENT "Forcing build step for '${proj}'"
     DEPENDEES configure
     DEPENDERS build
     ALWAYS 1