message: appleclang 10.01 does not have <filesystem>
  support
diff: @@ -11,7 +11,7 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "AppleClang")
  if(NOT VCPKG_ALLOW_APPLE_CLANG)
  message(FATAL_ERROR
  "Building the vcpkg tool requires support for the C++ Filesystem TS.
  -Apple clang versions 9 and below do not have support for it.
  +Apple clang versions 10.01 and below do not have support for it.
  Please install gcc6 or newer from homebrew (brew install gcc6).
  If you would like to try anyway, pass --allowAppleClang to bootstrap.sh.")
  else()
  