[gcc(refs/users/ppalka/heads/libstdcxx-constrained-algos)] Use iter_value_t instead of iterator_traits::value_type

[Patrick Palka]

https://gcc.gnu.org/g:21e21ae83cd89ee00965b549a8789a148f68b331

commit 21e21ae83cd89ee00965b549a8789a148f68b331
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Jan 28 13:59:56 2020 -0500

    Use iter_value_t instead of iterator_traits::value_type

Diff:
---
 libstdc++-v3/include/bits/ranges_algo.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h
index 8df5634..1e05bc3 100644
--- a/libstdc++-v3/include/bits/ranges_algo.h
+++ b/libstdc++-v3/include/bits/ranges_algo.h
@@ -771,8 +771,8 @@ namespace ranges
 	  if (__d1 != __d2)
 	    return false;
 
-	  using _ValueType1 = iterator_traits<_Iter1>::value_type;
-	  using _ValueType2 = iterator_traits<_Iter2>::value_type;
+	  using _ValueType1 = iter_value_t<_Iter1>;
+	  using _ValueType2 = iter_value_t<_Iter2>;
 	  constexpr bool __use_memcmp
 	    = ((is_integral_v<_ValueType1> || is_pointer_v<_ValueType1>)
 	       && is_same_v<_ValueType1, _ValueType2>