Rename ___make_pair_return to __make_pair_return_impl; ___make_tuple_return to __make_tuple_return_impl; and ____iterator_traits to __iterator_traits_impl. Part of a campaign to remove > 2 underscores from libc++. No functionality change.

llvm-svn: 198457
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 0724bf67672c754aa61ce2659939450ff22c30fa
diff --git a/include/iterator b/include/iterator
index 70a664d..c6dd033 100644
--- a/include/iterator
+++ b/include/iterator
@@ -364,10 +364,10 @@
     static const bool value = sizeof(__test<_Tp>(0)) == 1;
 };
 
-template <class _Iter, bool> struct ____iterator_traits {};
+template <class _Iter, bool> struct __iterator_traits_impl {};
 
 template <class _Iter>
-struct ____iterator_traits<_Iter, true>
+struct __iterator_traits_impl<_Iter, true>
 {
     typedef typename _Iter::difference_type   difference_type;
     typedef typename _Iter::value_type        value_type;
@@ -380,7 +380,7 @@
 
 template <class _Iter>
 struct __iterator_traits<_Iter, true>
-    :  ____iterator_traits
+    :  __iterator_traits_impl
       <
         _Iter,
         is_convertible<typename _Iter::iterator_category, input_iterator_tag>::value ||