[libc++] Implement P0591R4 (Utility functions to implement uses-allocator construction)

Reviewed By: ldionne, #libc, huixie90

Spies: huixie90, libcxx-commits, mgorny

Differential Revision: https://reviews.llvm.org/D131898

NOKEYCHECK=True
GitOrigin-RevId: 79df8e19beb9db218547bae5265139d0ff67343a
diff --git a/include/module.modulemap.in b/include/module.modulemap.in
index b7f3380..dd7fd08 100644
--- a/include/module.modulemap.in
+++ b/include/module.modulemap.in
@@ -878,6 +878,7 @@
       module uninitialized_algorithms        { private header "__memory/uninitialized_algorithms.h" }
       module unique_ptr                      { private header "__memory/unique_ptr.h" }
       module uses_allocator                  { private header "__memory/uses_allocator.h" }
+      module uses_allocator_construction     { private header "__memory/uses_allocator_construction.h" }
       module voidify                         { private header "__memory/voidify.h" }
     }
   }