[gn build] port 976f37050dbd more

Follow-up to commit 51d84737b5a.

GitOrigin-RevId: 35cc1738468e62453611fcb5d88d212da7022768
diff --git a/utils/gn/secondary/libcxx/include/BUILD.gn b/utils/gn/secondary/libcxx/include/BUILD.gn
index 6a7880c..6a1bc76 100644
--- a/utils/gn/secondary/libcxx/include/BUILD.gn
+++ b/utils/gn/secondary/libcxx/include/BUILD.gn
@@ -553,7 +553,6 @@
       "__ranges/zip_view.h",
       "__split_buffer",
       "__std_stream",
-      "__string",
       "__string/char_traits.h",
       "__string/extern_template_lists.h",
       "__support/android/locale_bionic.h",