[gn build] Port 97e383a

Author: llvmgnsyncbot

llvm/utils/gn/secondary/libcxx/include/BUILD.gn

@@ -73,6 +73,7 @@ if (current_toolchain == default_toolchain) {
       "__hash_table",
       "__iterator/concepts.h",
       "__iterator/incrementable_traits.h",
+      "__iterator/iter_move.h",
       "__iterator/iterator_traits.h",
       "__iterator/readable_traits.h",
       "__libcpp_version",