message: Workaround Python's map difference between Python2/3
  When the output of map is not used, using a list comprehension or an explicit
  call to list looks awkward.
diff: @@ -239,7 +239,8 @@ def check_out_if_needed(spec):
  def all_check_out_if_needed():
  - map(check_out_if_needed, XCODE_REPOSITORIES())
  + for r in XCODE_REPOSITORIES():
  + check_out_if_needed(r)
  def should_build_llvm():
  @@ -263,7 +264,8 @@ def setup_source_symlink(repo):
  def setup_source_symlinks():
  - map(setup_source_symlink, XCODE_REPOSITORIES())
  + for r in XCODE_REPOSITORIES():
  + setup_source_symlink(r)
  def setup_build_symlink():
  