message: Update to clang 9.* (removed libc++fs)
diff: @@ -38,6 +38,10 @@ If you would like to try anyway, pass --allowAppleClang to bootstrap.sh.")
  endif()
  elseif(CMAKE_CXX_COMPILER_ID MATCHES "[Cc]lang")
  set(CLANG 1)
  + if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "9.0.0")
  + set(NO_LIBCXXFS 1)
  + add_compile_definitions(_LIBCPP_NO_EXPERIMENTAL_DEPRECATION_WARNING_FILESYSTEM=1)
  + endif()
  elseif(NOT MSVC)
  message(FATAL_ERROR "Unknown compiler: ${CMAKE_CXX_COMPILER_ID}")
  endif()
  