message: Use DESCRIPTION only if CMake version >= 3.9
diff: if (POLICY CMP0048)
  cmake_policy(SET CMP0048 NEW)
  + if(CMAKE_VERSION VERSION_LESS 3.9)
  + project(FlatBuffers
  + VERSION 2.0.0
  + LANGUAGES CXX)
  + else()
  project(FlatBuffers
  DESCRIPTION "Flatbuffers serialization library"
  VERSION 2.0.0
  LANGUAGES CXX)
  + endif()
  else()
  project(FlatBuffers)
  endif (POLICY CMP0048)
  