Add constexpr to pair

Reviewed By: #libc, ldionne

Differential Revision: https://reviews.llvm.org/D80558

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 737a4501e815d8dd57e5095dbbbede500dfa8ccb
diff --git a/include/version b/include/version
index acedd03..dc53be3 100644
--- a/include/version
+++ b/include/version
@@ -42,6 +42,7 @@
 __cpp_lib_constexpr_misc                                201811L <array> <functional> <iterator>
                                                                 <string_view> <tuple> <utility>
 __cpp_lib_constexpr_swap_algorithms                     201806L <algorithm>
+__cpp_lib_constexpr_utility                             201811L <utility>
 __cpp_lib_destroying_delete                             201806L <new>
 __cpp_lib_enable_shared_from_this                       201603L <memory>
 __cpp_lib_endian                                        201907L <bit>
@@ -227,6 +228,7 @@
 // # define __cpp_lib_concepts                             201806L
 // # define __cpp_lib_constexpr_misc                       201811L
 // # define __cpp_lib_constexpr_swap_algorithms            201806L
+# define __cpp_lib_constexpr_utility                    201811L
 # if _LIBCPP_STD_VER > 17 && defined(__cpp_impl_destroying_delete) && __cpp_impl_destroying_delete >= 201806L
 #   define __cpp_lib_destroying_delete                  201806L
 # endif