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.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@198457 91177308-0d34-0410-b5e6-96231b3b80d8
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 ||
diff --git a/include/tuple b/include/tuple
index a1a7bcf..24e086d 100644
--- a/include/tuple
+++ b/include/tuple
@@ -816,13 +816,13 @@
 template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
 
 template <class _Tp>
-struct ___make_tuple_return
+struct __make_tuple_return_impl
 {
     typedef _Tp type;
 };
 
 template <class _Tp>
-struct ___make_tuple_return<reference_wrapper<_Tp> >
+struct __make_tuple_return_impl<reference_wrapper<_Tp> >
 {
     typedef _Tp& type;
 };
@@ -830,7 +830,7 @@
 template <class _Tp>
 struct __make_tuple_return
 {
-    typedef typename ___make_tuple_return<typename decay<_Tp>::type>::type type;
+    typedef typename __make_tuple_return_impl<typename decay<_Tp>::type>::type type;
 };
 
 template <class... _Tp>
diff --git a/include/utility b/include/utility
index 2c1f62c..0a1a7f1 100644
--- a/include/utility
+++ b/include/utility
@@ -465,13 +465,13 @@
 template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
 
 template <class _Tp>
-struct ___make_pair_return
+struct __make_pair_return_impl
 {
     typedef _Tp type;
 };
 
 template <class _Tp>
-struct ___make_pair_return<reference_wrapper<_Tp>>
+struct __make_pair_return_impl<reference_wrapper<_Tp>>
 {
     typedef _Tp& type;
 };
@@ -479,7 +479,7 @@
 template <class _Tp>
 struct __make_pair_return
 {
-    typedef typename ___make_pair_return<typename decay<_Tp>::type>::type type;
+    typedef typename __make_pair_return_impl<typename decay<_Tp>::type>::type type;
 };
 
 template <class _T1, class _T2>