message: Improve check compilator version.
diff: @@ -168,12 +168,14 @@ if(UNIX)
  set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
  endif(APPLE)
  if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
  - if(COMPILER_VERSION VERSION_LESS 3.8 )
  - message(FATAL_ERROR "RINGMesh require Clang version >= 3.8")
  + set(supported_clang_version 3.8)
  + if(COMPILER_VERSION VERSION_LESS ${supported_clang_version})
  + message(FATAL_ERROR "RINGMesh require Clang version >= ${supported_clang_version}")
  endif()
  elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
  - if(COMPILER_VERSION VERSION_LESS 4.8 )
  - message(FATAL_ERROR "RINGMesh require G++ version >= 4.8")
  + set(supported_gcc_version 4.8)
  + if(COMPILER_VERSION VERSION_LESS ${supported_gcc_version})
  + message(FATAL_ERROR "RINGMesh require G++ version >= ${supported_gcc_version}")
  endif()
  endif()
  # In Cmake > 3, there is the option: set (CMAKE_CXX_STANDARD 11). To see in the future.
  