message: GREATER_EQUAL only available since CMake v3.7
diff: @@ -24,10 +24,10 @@ IF (NOT ISPC_EXECUTABLE)
  SET(ISPC_DIR_SUFFIX "osx")
  ELSEIF(WIN32)
  SET(ISPC_DIR_SUFFIX "windows")
  - IF (MSVC_VERSION GREATER_EQUAL 1900)
  - LIST(APPEND ISPC_DIR_SUFFIX "windows-vs2015")
  - ELSE()
  + IF (MSVC_VERSION LESS 1900)
  LIST(APPEND ISPC_DIR_SUFFIX "windows-vs2013")
  + ELSE()
  + LIST(APPEND ISPC_DIR_SUFFIX "windows-vs2015")
  ENDIF()
  ELSE()
  SET(ISPC_DIR_SUFFIX "linux")
  